Strange space signal could come from a ‘mystery object’

It’s too big to be a neutron star, but too small to be a black hole.

An artists’ impression shows a black hole swallowing a mysterious smaller object in deep space.
(Image: © @Alex Andrix/Virgo/EGO)

A signal from space first detected Aug. 14, 2019, may have come from a mystery object. And it might force physicists to rip up an old idea about black holes and neutron stars.

The signal was a gravitational wave, a ripple in space-time labeled GW190814, and seemed to indicate the collision of two wildly mismatched objects. The larger one was definitely a black hole, about 23 times the mass of our sun. And the smaller one was either a black hole or a neutron star, about 2.6 times the mass of our sun. There’s just one problem: There’s never been evidence that black holes or neutron stars of that size even existed.

Astronomers have never detected black holes lighter than five times the mass of the sun. And neutron stars seem to max out well below 2.5 solar masses. In between the two is a “mass gap” where, for uncertain reasons, no compact objects seemed to form. Until now.

(There have been occasional, tentative reports of objects in the mass gap before, but this gravitational wave seems to offer the most compelling evidence.)

her also based at Northwestern University, said in the statement.

There are some preliminary ideas about what might be going on here, Spera said. Dense, active cores of hot galaxies might produce lopsided pairs of celestial objects. Newly-formed star clusters might do the same.

“However, what we know for sure and so far is that the universe is firmly telling us that we are still missing most of the story on the formation and evolution of compact objects,” he said.

A paper describing the mysterious collision was published June 23 in The Astrophysical Journal Letters.

Originally published on Live Science.

By Rafi Letzter – Staff Writer




Scientists just sampled the most pristine air on Earth. Here’s what they found.

What happens if you turn space-time upside-down?

(Image: © Shutterstock)

The Southern Ocean is a vast band of open water that encircles the entire planet between Antarctica and the Southern Hemisphere landmasses. It is the cloudiest place on Earth, and the amount of sunlight that reflects off or passes through those clouds plays a surprisingly important role in global climate. It affects weather patterns, ocean currents, Antarctic sea ice cover, sea surface temperature and even rainfall in the tropics.

But due to how remote the Southern Ocean is, there have been very few actual studies of the clouds there. Because of this lack of data, computer models that simulate present and future climates overpredict how much sunlight reaches the ocean surface compared to what satellites actually observe. The main reason for this inaccuracy is due to how the models simulate clouds, but nobody knew exactly why the clouds were off. For the models to run correctly, researchers needed to understand how the clouds were being formed.

To discover what is actually happening in clouds over the Southern Ocean, a small army of atmospheric scientists, including us, went to find out how and when clouds form in this remote part of the world. What we found was surprising — unlike the Northern Hemisphere oceans, the air we sampled over the Southern Ocean contained almost no particles from land. This means the clouds might be different from those above other oceans, and we can use this knowledge to help improve the climate models.

Ice clouds and liquid clouds

Clouds are made of tiny water droplets or ice crystals, or often a mixture of the two. These form on small particles in the air. The type of particle plays a big role in determining whether a liquid droplet or ice crystal forms. These particles can be natural — like sea spray, pollen, dust or even bacteria — or from human sources like cars, stoves, power plants and so on.

To the untrained eye, an ice cloud and a liquid cloud look much the same, but they have very different properties. Ice clouds reflect less sunlight, precipitate more and don’t last as long as liquid clouds. It matters to the weather — and to climate models — what kinds of clouds are around.

Climate models tend to predict too many ice clouds over the Southern Ocean and not enough liquid clouds when compared to satellite readings. But satellite measurements around the poles are hard to make and less accurate than other regions, so we wanted to collect direct evidence of how many liquid clouds are actually present and determine why there were more than the models predict.

This was the mystery: Why are there more liquid clouds than the models think there are? To solve it, we needed to know what kinds of particles are floating around in the atmosphere around Antarctica.

Before we went down there, we had a few clues.

Previous modeling studies have suggested that the ice–forming particles found over the Southern Ocean may be very different from those found in the Northern Hemisphere. Dust is a great ice cloud seeder, but due to the lack of dusty land sources in the Southern Hemisphere, some scientists have hypothesized that other types of particles might be driving ice cloud formation over the Southern Ocean.

Since most models are based on data from the Northern Hemisphere, if the particles in the atmosphere were somehow different in the Southern Hemisphere, that might explain the errors.

Bacterial maps

It’s hard to directly measure the composition of particles over the Southern Ocean — there simply aren’t very many particles around. So, to help us track down what is inside the clouds, we used an indirect approach: the bacteria in the air.

The atmosphere is full of microorganisms that are carried hundreds to thousands of kilometers on air currents before returning to Earth. These bacteria are like airborne license plates, they are unique and tell you where the car — or air — came from. Since scientists know where most bacteria live, it’s possible to look at the microbes in an air sample and determine where that air came from. And once you know that, you can predict where the particles in the air came from as well – the same place the bacteria usually live.

In order to sample airborne bacteria in this remote ocean region, one of us headed out on the Australian Marine National Facility’s R/V Investigator for a six-week expedition. The weather was unruly and the waves were often white-capped, but for one to two days at a time, we sucked air from the bow of the ship through a filter that caught the airborne particles and bacteria. We then froze the filters to keep the bacterial DNA intact.

Ocean bacteria alone

In most ocean regions around the world, especially in the Northern Hemisphere where there is a lot of land, the air contains both marine and terrestrial particles. That’s what we expected to find down south.

With the frozen filters safely back at our lab in Colorado, we extracted DNA from the bacteria and sequenced it to determine what species we had caught. Much to our surprise, the bacteria were essentially all marine species that live in the Southern Ocean. We found almost no land-based bacteria.

If the bacteria were from the ocean, then so were the cloud-forming particles. This was the answer we were looking for.

Ice nucleating particles are very rare in seawater and marine particles are very good at forming liquid clouds. With mostly marine-based particles in the air, we’d expect the clouds to mostly be made of liquid droplets, which is what we observed. Since most models treat clouds in this region the same way they do clouds in the dustier Northern Hemisphere, it’s no wonder the models were off.

Going forward

Now that we know the summertime Southern Ocean clouds are being formed from purely marine particles, we need to figure out if the same is true in other seasons and at higher altitudes. The larger project, which involved planes as well as ships, has given atmospheric scientists a much better idea of the clouds both close to the ocean surface and high up in the atmosphere. The climate modelers among us are already incorporating these new data into their models and will hopefully have results to share soon.

Discovering that the airborne particles over the Southern Ocean are mostly coming from the ocean is a remarkable finding. It not only improves global climate models, it also means we confirmed the Southern Ocean is one of the most environmentally pristine regions on Earth — a place that has probably changed very little due to human activities. Our work will hopefully improve climate models, but has also given researchers a baseline for what a truly pristine marine environment looks like.

By Kathryn Moore – Colorado State University, Jun Uetake – Colorado State University, Thomas Hill – Colorado State University





Why some physicists really think there’s a ‘mirror universe’ hiding in space-time

What happens if you turn space-time upside-down?

The Cosmic Microwave Background, pictured here, is the most ancient thing we can see in space. But what’s hiding behind it?
(Image: © ESA and the Planck Collaboration)

A series of viral articles claimed that NASA had discovered particles from another parallel universe in which time runs backward. These claims were incorrect. The true story is far more exciting and strange, involving a journey into the Big Bang and out the other side.

The sensational headlines had muddled the findings of an obscure 2018 paper, never published in a peer-reviewed journal, which argued that our universe might have a mirror reflection across time, a partner universe that stretches beyond the Big Bang. If that’s the case, and a series of other extremely unlikely and outlandish hypotheses turn out to be true, the paper argued, then that in turn could explain a mysterious signal hinting that a completely new particle is flying out of the ice in Antarctica.

Related: The 11 Biggest Unanswered Questions About Dark Matter

The claim that NASA discovered a parallel universe seemed to have been first dreamed up by British tabloid The Daily Star, and the story was then picked up by British and American outlets, including The New York Post.

Screenshots show false “parallel universe” claims in several publications. (Image credit: Illustration by Live Science)

Our universe’s “mirror”

In order to understand how The Daily Star arrived at its bizarre, viral claim, it’s necessary to understand the claims of two separate papers from 2018.

The first paper, by Latham Boyle, a physicist at The Perimeter Institute in Alberta, Canada, and his colleagues, proposed a mirror universe — a reflection of our universe across time. It was published December 2018 in the journal Physical Review Letters (after an appearance on the arXiv server in March that year).

“I think nobody else understands the full sweep of what they have composed,” said John Learned, a University of Hawaii astrophysicist and the co-author of a second paper, which builds on Boyle’s theory.

Boyle’s work is a kind of expansion pack meant to plug holes in the theory that tells the dominant  origin story of the universe: Lambda-Cold Dark Matter (ΛCDM).

ΛCDM explains the cosmos using two key ideas: An unknown dark energy causes the universe to expand. Rewind that expansion far enough backward in time and the whole universe occupies a single point in space. Second, an unseen dark matter gravitationally tugs on stuff in the universe, yet emits no light. This dark matter, the idea goes, accounts for the vast majority of the universe’s mass.

“ΛCDM is basically the only game in town,” Learned said. “It works in many cases, but there are some somewhat disturbing lapses in the modeling.”

For instance, measurements of expansion don’t line up across time, so that measurements made of this expansion based on data from the early universe don’t jive with measurements using data from the modern universe. In addition, ΛCDM can’t explain why matter exists at all, since it predicts that matter and antimatter would have formed at equal rates after the Big Bang, and annihilated each other, leaving nothing behind.

Related: Big Bang to present: Snapshots of our universe through time

Boyle and his colleagues’ new universe unwinds the ΛCDM story further back in time, diving into the singularity at the beginning of time and coming out the other side.

Here’s how Boyle’s team sees their theory: Imagine today’s universe as a wide, flat circle, sitting on top of yesterday’s slightly smaller circle, which sits on top of the yet-smaller circle of the day before that, Boyle said.

(Image credit: Meghan McCarter)

Stack up all the circles from today back to the Big Bang, and you’d end up with a cone standing on its point end.

(Image credit: Meghan McCarter)

When astronomers look deep into space, they’re effectively looking back in time. The most distant galaxy we can see, GN-z11, appears to us as it existed 13.4 billion years ago, or 400 million years after the Big Bang.

Before that, the universe had a “dark age” lasting millions of years, where nothing bright enough for us to see formed. Before that, the universe produced the oldest thing we can see: the Cosmic Microwave Background (CMB), which formed 370,000 years after the Big Bang, as the universe cooled out of a hot, opaque plasma.

Telescopes can’t see anything from before the CMB.

Looking back in time like this, Boyle said, is like looking down through the cosmological cone.

(Image credit: Meghan McCarter)

Viewed in this way, the ΛCDM story ends with the universe coming together into a single point hidden behind the CMB. Boyle’s theory looks at the opaque wall the CMB forms across time and draws a different conclusion about what the CMB hides.

The standard view, he said, is that the hot, dense era below the CMB (from our vantage point on the cone) was more or less a “big mess.” In ΛCDM cosmology, this is the accelerated period of expansion known as “the epoch of inflation.” Back then everything was chaos, the theory states.

But the CMB isn’t that chaotic. Its simple structure, according to ΛCDM, emerged after an intense flattening process that wiped away the old mess.

Related: What’s that? Your physics questions answered

“We were interested in exploring a simpler picture where you take the evidence more at face value,” he said. “You say ‘Okay, we can’t see all the way down to the Bang, but we can look darned close, and as close as we look things look super simple. What if we take those observations at face value?'”

This vision of space-time still has a Big Bang hiding behind the CMB, he said.

But “it’s much simpler than most of the singularities that arise in Einstein’s theory of gravity,” he said. “It’s a very special type of ultra-simple singularity, where you can follow the solution [to the equations governing space-time] through the singularity.”

Whereas observations go no further back than the CMB, normal cosmological models go a bit further back but still tend to come to a hard stop at the Big Bang. Not in Boyle’s scheme.

“You find that it extrapolates, it extends — it analytically continues, physicists would say, to this double cone,” he said, referring to the second universe extending away from the Big Bang in time

(Image credit: Meghan McCarter)

“It just seems to be the natural, simplest extension of the equations that seem to describe the universe as we see it,” he said.

This universe that’s inside the “second cone” is too far down space-time for us to see. Time might seem to run backward there from our reference frame, Learned said. But beings in that universe would still see cause coming before effect, just like we do in ours. Time runs away from the Big Bang in that universe, just like it does in ours. “Away from the Big Bang” in that universe is the opposite direction from the direction of time in our universe. but it doesn’t run “backward” in the way we might imagine.

Related: 5 reasons we may live in a multiverse

Our universe exists on the other side of that universe’s ancient history, and that universe exists on the other side of ours.

The “zero particle state”

We have no evidence that this reflected universe exists, Boyle said.

However, he said, “once you have it, it turns out this universe has an extra symmetry, which you didn’t see when you were just looking at the top half of the cone.”

Symmetries “ring a loud bell” for physicists, Boyle said. They suggest deeper truth.

And this double-cone universe could, in turn, help restore a crack in a symmetry that has bothered physicists for years.

The symmetry in question, known as Charge, Parity, Time (CPT) symmetry states that if you flip a particle to its antimatter twin — an electron into a positron, say — or make it right-handed instead of left-handed, or move it backward through time instead of forward, that particle should still behave in the same way and obey the same laws as it did before getting flipped. (Right-handed or left-handed refers to a particle’s spin and direction of movement.)

“Everybody thought these were fundamental symmetries that could not be escaped,” Learned said.

Eventually, in 1956, the Columbia University physicist Chien-Shiun Wu led an experiment that established CPT symmetry wasn’t absolute. (The two male colleagues who proposed the underlying idea to Wu won the 1957 Nobel Prize for her discovery, but she was left out.)

Wu’s experiment showed that the “C” in CPT symmetry is imperfect. And further experiments showed that some particles break both “C” and “P.” But though cracked, most physicists think CPT symmetry still holds in general, and no particle has been found that breaks all three elements of this symmetry. At the particle level, the universe appears CPT symmetric.

But the ΛCDM model of the universe itself lacks clear CPT symmetry — a consequence of the curvature of space-time and the strange quantum vacuum. A feature of the universe that Boyle called its “zero particle state,” the nature of space-time when emptied of particles, is uncertain. That means that at the scale of all space, CPT symmetry is violated.

Boyle says that his model preserves the universe’s CPT symmetry in a way the ΛCDM cosmology does not. Add a second cone to space-time, and the zero particle state is no longer uncertain. The universe’s CPT asymmetry is repaired.

“We thought, ‘Wait a minute. It seemed like the universe violated CPT symmetry, but actually we just weren’t looking at the whole picture,” he said. If the universe really is CPT-symmetric, if it really comprises two space-time cones rather than one, what would that mean for the rest of physics?

The truth behind what those “NASA scientists” really detected

The most practical consequence of the CPT-symmetric universe is a simple explanation for dark matter.

One popular set of theories about the unseen stuff relies on the existence of some undetected, fourth type of neutrino — often termed a sterile neutrino. Boyle’s CPT symmetry seems to point in this direction. The three known flavors of neutrino, the electron, muon and tau neutrinos, are all left-handed. That means that they fly around without a matching right-handed partner. The Standard Model assumes that, unlike other particles, neutrinos don’t have such partners. But the CPT-symmetric universe disagrees, indicating they should have those partners.

Boyle and his colleagues found that their cosmology implies the existence of a right-handed partner in our universe for every left-handed neutrino in the Standard Model. But, unlike left- and right-handed quarks, these left- and right-handed mirror particles wouldn’t stick together.Instead, two of the right-handed partner neutrinos would have long since been lost to space-time, decaying out of our view in the very early universe. A third right-handed partner would have stuck around, however ⁠— a consequence of the equations governing the beginning of time.

It’s not clear which of the three known neutrinos it would have partnered with, Boyle said. But it would have had a particular energy signature: 480 picoelectronvolts (PeV), a measure of a particle’s mass. And that 480PeV neutrino might account for all of that missing dark matter in the universe.

The details of how the CPT-symmetric universe leads to a 480 PeV neutrino are tricky — so tricky, Learned said, that few physicists beyond Boyle and his team understand them at all.

“But these guys are not nutcases,” he said. “They’re respected members of the field and they know what they’re doing. Whether all of that complicated field theory is correct or not, I can’t say.”

Still, the prediction of a 480 PeV particle jumped out at Learned.

Four years ago, a particle detector hanging from a balloon over Antarctica detected something physics could not explain: Twice, as Live Science previously reported, the Antarctic Impulsive Transient Antenna (ANITA) instrument picked up signals of high-energy particles that seemed to shoot straight up out of the Antarctic ice. (Most researchers involved in ANITA aren’t “NASA scientists,” but the project does receive NASA funding.)

Researchers prepare to launch the Antarctic Impulsive Transient Antenna (ANITA) experiment, which picked up signals of impossible-seeming particles as it dangled from its balloon over Antarctica. (Image credit: NASA)

Particles like this shouldn’t exist. None of the known Standard Model particles should have been able to fly all the way through the Earth and burst out the other side at such high energies, but that’s what ANITA seemed to be detecting.

As of June 2020, the most popular explanation is that ANITA has detected sterile neutrinos. Learned, who was involved in the early days of the ANITA project, realized the 480 PeV figure lined up nicely with the ANITA findings.

If particles really came from space, then plunged through the Earth to produce the anomaly, they must have decayed just under the Antarctic surface, producing a shower of lighter particles that ANITA detected popping up from the ice. Boyle’s 480 PeV dark matter neutrino fit squarely in the mass range that could explain ANITA’s decaying mystery particle.

Learned and a team of four other researchers cooked up a scheme where this 480 PeV dark matter neutrino might have pulled off this trick, which they wrote up in a 2018 paper titled “Upgoing ANITA events as evidence of the CPT symmetric universe” and published to the arXiv database. This is the paper The Daily Star turned into a confused headline.

If the ANITA particle really did fit Boyle’s scheme, that would be a strong weight on the scale in favor of the two-cone cosmos, Learned said. But it’s a long shot. The most important problem they had to solve: getting the particle close enough to Antarctica. Models show that dark matter candidate particles like this 480 PeV neutrino would fall to the center of the Earth soon after running into our planet, leaving none close enough to produce the ANITA anomaly.

These researchers argued that perhaps a recent encounter with a huge, unseen disk of dark matter has stirred up the Earth’s 480 PeV neutrinos, leaving some wandering around close to our planet’s surface.

It was an exciting idea to play with, Learned said, but even he is not convinced by his own paper.

“That was our feeble excuse, not thinking of any other good way to do the job [of getting Boyle’s neutrinos close enough to Antarctica to trip ANITA’s sensors],” Learned said.Though Learned and his colleagues worked hard on the paper, he thinks its conclusions are surely wrong, he said.

“Amongst cosmology folks there’s … an idea that you get to use a ‘tooth fairy’ once in your cosmology model but twice is simply not credible,” he said. “And I think we needed the tooth fairy two or three times to make this one work, so, oh well.”

Boyle agreed. While the idea of using his team’s ideas to explain ANITA was appealing, he said the numbers don’t quite add up. But he’s still confident the underlying idea of a CPT-symmetric universe is sound.

“My personal hunch is that whether or not it’s exactly correct, it’s on the right track,” he said. “I’m very excited about that.”

Originally published on Live Science.
By Rafi Letzter – Staff Writer




3877: Ancient Antarctic sea monster may have laid this football-size egg

A mosasaur, an ancient reptile that lived during the Mesozoic, might have laid the newly described fossil egg found in Antarctica.
(Image: © Francisco Hueichaleo, 2020)

A 68 million-year-old egg the size of a football — the largest soft-shelled egg on record and the second largest egg ever discovered — might belong to a mosasaur, a reptilian sea monster that lived during the age of dinosaurs in what is now Antarctica, a new study finds.

If true, this would be the only mosasaur egg on record, according to the study, published online yesterday (June 17) in the journal Nature.

“There’s no known egg like this,” study senior researcher Julia Clarke, a professor of vertebrate paleontology at the University of Texas at Austin (UT Austin), told Live Science. “This egg is exceptional in both its size and its structure.”

Related: Photos: Fossilized dino embryo is new oviraptorosaur species

Chilean researchers found the eggs-traordinary fossil in a seasonal stream in 2011, about 660 feet (200 meters) away from the remains of 33-foot-long (10 m) Kaikaifilu hervei, a large mosasaur unearthed on Seymour Island, Antarctica, said study co-researcher David Rubilar-Rogers, a paleontologist at the National Museum of Natural History (MNHN) in Santiago, Chile. Despite the egg’s proximity to the mosasaur, however, “the identity of the animal that laid the egg is unknown,” the researchers wrote in the study.

“Although we weren’t clear on what it was, the strangeness of its shape was enough to collect it and take it to camp,” Rubilar-Rogers told Live Science in an email translated from Spanish. The fossil was so bizarre, the team called it “The Thing,” after the 1982 sci-fi movie based in Antarctica, which the paleontologists bravely watched when they were stuck in their tents due to bad weather, study co-researcher Rodrigo Otero, a paleontologist at the University of Chile in Santiago, told Live Science.

The Thing sat in the MNHN until 2018, when Clarke visited and struck up a conversation with Rubilar-Rogers about how Antarctica didn’t have any known fossilized eggs. On a hunch, he showed her The Thing. “To me, it looked exactly like a deflated football,” Clarke recalled.

The following analysis, however, revealed it was an exceptional find. At about 11 inches by 8 inches (29 by 20 centimeters), it’s second in size only to the egg of the extinct Madagascan elephant bird (Aepyornis maximus). It’s also the only known fossil egg ever found in Antarctica.

The fossil egg is the largest known soft-shelled egg in the world.
The fossil egg is the largest known soft-shelled egg in the world. (Image credit: Legendre et al. (2020))

This is how the mosasaur might have laid the egg. (Image credit: Francisco Hueichaleo, 2020)

The soft-shelled egg filled with sediment (and an ammonite) before it fossilized. (Image credit: Legendre et al. (2020))

The mosasaur might have laid the egg underwater (as some sea snakes do today) or on land (as modern sea turtles do).The mosasaur might have laid the egg underwater (as some sea snakes do today) or on land (as modern sea turtles do). (Image credit: Legendre et al. (2020)

Is it really a mosasaur?

The newfound egg, dubbed Antarcticoolithus bradyi (or “delayed Antarctic stone egg” in Greek), pushes the limits of how large scientists thought soft-shelled eggs could grow. In contrast to the hard-shelled elephant bird’s egg — which was five times thicker than this one — A. bradyi has a thin eggshell that lacks pores. These features also set A. bradyi  apart from most ancient dinosaur eggs.

“It is from an animal the size of a large dinosaur, but it is completely unlike a dinosaur egg,” study lead researcher Lucas Legendre, a postdoctoral researcher at UT Austin’s Jackson School of Geosciences, said in a statement. “It is most similar to the eggs of lizards and snakes, but it is from a truly giant relative of these animals.”

Like lizards and snakes, mosasaurs fall into the Lepidosauria group. Though the baby that incubated within the egg is long gone (the team did find an ammonite inside of it, however), the team said there are clues that it was a mosasaur. For instance, there aren’t any known late Cretaceous Antarctic dinosaurs or pterosaurs large enough to have laid such a huge egg, Clarke said. But the remains of the contemporary K. hervei are nearby.

An analysis of 259 living lepidosaur species and their eggs suggested that A. bradyi belonged to a mother measuring at least 23 feet (7 m) long, not including the tail. It’s possible that during the late Cretaceous this area of Antarctica was a nursery, as paleontologists have also found fossils of baby mosasaurs and plesiosaurs there, along with adult remains.

Related: 15 of the Largest Animals of Their Kind on Earth

Dinosaurs laid soft-shelled eggs, too

The soft-shelled egg finding is “pretty spectacular,” said Darla Zelenitsky, an assistant professor of dinosaur paleobiology at the University of Calgary in Canada, who wasn’t involved in the research. “Soft-shelled eggs consist almost entirely of membranes, so these soft tissues are quite fragile and destructible. Because of this, for many years we thought that fossilization of such eggs was nearly impossible.”

Until now, many researchers didn’t think that mosasaurs laid eggs, the authors noted. If A. bradyi is a mosasaur egg, it would “represent one of the first known instances of live birth in an ancient, extinct species of the snake and lizard family,” Zelenitsky told Live Science in an email.

Zelenitsky is the senior researcher on another study also published in Nature yesterday suggesting that the first dinosaur eggs had soft shells. Their conclusion is based on the discovery of fossilized soft eggshells from the horned dinosaur Protoceratops, which lived during the Cretaceous period, and the Triassic period sauropodomorph Mussaurus.

Given that Zelenitsky’s study found soft-shelled dinosaur eggs, perhaps A. bradyi actually came from dinosaur eggs laid on land that then washed out to sea, two Swedish researchers wrote in an accompanying opinion piece in Nature.

Zelenitsky, too, thought that “the new egg looks a lot like the soft-shelled eggs of dinosaurs. Perhaps an analysis comparing the soft tissue of A. bradyi with those of other reptile eggs could shed light on what kind of animal laid it, she said.

Originally published on Live Science.
By Laura Geggel – Associate Editor




‘It’s not ours’: Government denies knowledge of strange ‘UFO’ over Japanese city

It looks like a weather balloon, but the Japan Meteorological Agency denies it’s theirs.

An unidentified flying object (UFO) was seen above Aoba Ward in Sendai, Japan, on the morning of June 17, 2020.
(Image: © STR/JIJI PRESS/AFP via Getty Images)

It’s not a bird. It’s not a plane. And it’s not an alien. (It’s never an alien, from planet Krypton or otherwise.)

Still, the origin of a strange, balloon-like UFO that appeared in the sky over the city of Sendai, Japan, yesterday (June 17) around 7 a.m. local time, remains a mystery a full day after its sudden arrival. The object looked like a large white, unmanned balloon attached to two crossed propellers, according to news reports. The UFO lingered in the sky, largely motionless, for several hours before drifting over the Pacific Ocean, AFP reported.

Reuters India


WATCH: A balloon-like object in the sky over northern Japan sparks debate on social media

While a weather balloon seems like the obvious explanation (they are widely available for purchase), a spokesperson from the Sendai bureau of the Japan Meteorological Agency told AFP that “it’s not ours.” In his daily press briefing later that day, Japan’s Chief Cabinet Secretary Yoshihide Suga also denied any knowledge of the balloon’s origin, according to AFP.

Suga also tried to pop any rumors that the balloony UFO was the dastardly instrument of a foreign government. Earlier on Wednesday, social media speculation about the object ran rampant, giving air to theories that the UFO was distributing North Korean propaganda or even spreading the novel coronavirus.

The evidence for either of these theories — much like the balloon itself — looks like a big, fat goose egg. For a truly head-scratching UFO mystery, grab a tinfoil hat and take a look at these eerie airborne videos recently declassified by the U.S. government.

By Brandon Specktor – Senior Writer




The monstrous ‘blobs’ near Earth’s core may be even bigger than we thought

The mysterious ‘blobs’ near Earth’s core just got a little bigger.

Earthquakes (stars) send seismic waves rippling through the planet. Seismometers (blue triangles) detect them on the other side. Thirty years of seismic data revealed where those seismic waves slowed down (purple and orange splotches), pointing to mysterious inner-Earth structures called ultralow-velocity zones.
(Image: © Doyeon Kim/University of Maryland)

Deep within Earth, where the solid mantle meets the molten outer core, strange continent-size blobs of hot rock jut out for hundreds of miles in every direction. These underground mountains go by many names: “thermo-chemical piles,” “large low-shear velocity provinces” (LLSVPs), or sometimes just “the blobs.”

Geologists don’t know much about where these blobs came from or what they are, but they do know that they’re gargantuan. The two biggest blobs, which sit deep below the Pacific Ocean and Africa, account for nearly 10% of the entire mantle’s mass, one 2016 study found — and, if they sat on Earth’s surface, the duo would each extend about 100 times higher than Mount Everest. However, new research suggests, even those lofty analogies may be underestimating just how big the blobs really are.

In a study published June 12 in the journal Science, researchers analyzed the seismic waves generated by earthquakes over nearly 30 years. They found several massive, never before-detected features along the edges of the Pacific blob.

“The structures we located are … thousands of kilometers across in scale,” lead study author Doyeon Kim, a postdoctoral fellow at the University of Maryland, told Live Science in an email. According to Kim, that’s an order of magnitude larger than typical features found along the blob’s edge.

Related: The 9 best blobs of 2019

A map of trembling Earth

Because the blobs live deep, deep in Earth’s interior, geologists can only begin to understand their shape and size by looking at the seismic waves (sound waves generated by earthquakes) that travel through them. These hot, dense regions can slow incoming waves by up to 30% relative to the surrounding mantle; the hottest, slowest regions are known as ultralow-velocity zones (ULVZs), and they typically occur near the edges of the blobs, Kim said.

In their study, Kim and his colleagues created a new map of ULVZs below the Pacific Ocean using an algorithm called “the Sequencer,” which was originally developed to find patterns in stellar radiation. With this algorithm, the team analyzed 7,000 seismograms, or measures of seismic waves, collected between 1990 and 2018, created by hundreds of earthquakes of magnitude 6.5 or greater. The earthquakes occurred in Asia and Oceania, the researchers wrote; but as their seismic waves shuddered across the globe, they passed clearly through the Pacific Ocean mantle blob before reaching seismometers in the United States.

A map of inner Earth showing the new ultralow-velocity zones (yellow outline) mapped through 30 years of seismic data. (Image credit: Doyeon Kim/University of Maryland)

The algorithm revealed enormous sections of ULVZs never detected before, including a blobby region below the Marquesas Islands in the South Pacific Ocean, which measured more than 620 miles (1,000 kilometers) across. The Sequencer also showed that a segment of the blob deep below the Hawaiian Islands is considerably larger than previously thought.

“By looking at thousands of core-mantle boundary [seismograms] at once, instead of focusing on a few at a time, we have gotten a totally new perspective,” Kim said in a statement.

The enormous size of these structures suggests that blobs along the core-mantle boundary — and particularly the hottest, densest ULVZs — are probably more widespread than previous research indicates. What’s more, Kim added, the fact that these large zones lurk near known volcanic hotspots could also reveal some clues about their impact on Earth’s geology.

It’s possible, for example, that ULVZs deep down in the mantle could feed into the large “plumes” of hot rock in the upper mantle that create volcanic hot spots on the surface, Kim said. Those mantle plumes might “suck on” the melty material collected in ULVZs and pull it upward, which could explain why the largest ULVZs are located deep under volcanic island chains like the Hawaiian and Marquesas islands.

That’s just one theory, Kim said; even with algorithms designed to pierce the void of space, the mysteries near the center of the Earth remain just as murky as ever.

“In short, everything is unsure at the moment,” Kim said, “but this is what makes our field of study so exciting.”

Originally published on Live Science.
By Brandon Specktor – Senior Writer




3870: Mysterious blue fireball streaks above Western Australia, puzzling astronomers

The strange fireball was caught on video.

A streak of blue light that flashed across the sky on Monday surprised western Australia’s night owls and befuddled the astronomy community.

The blue fireball was seen at 1 a.m. local time on June 15, according to ABC News Pilbara. “It was really a spectacular observation,” Glen Nagle, the education and outreach manager at the CSIRO-NASA tracking station in Canberra, told the news agency. Sightings were reported across the remote Pilbara region as well as in the country’s Northern Territory and in South Australia, Nagle said.

Many observers caught the phenomenon on video. The fireball streaks steadily across the sky. At first, it appears orange or yellow, with a short tail streaming behind it. After a few seconds, the bulk of the fireball lights up blue.

Related: 7 things most often mistaken for UFOs

Scientists aren’t quite sure what object was burning up in the atmosphere to create the brilliant light show, according to ABC News. Some amateur astronomers speculated that the object could be human-made debris, perhaps from a recent rocket launch. But that seems unlikely, Renae Sayers, a research ambassador at Curtin University’s Space Science and Technology Centre, told the news agency.

James Hirsen @thejimjams

A fireball flashes across the night sky in Western Australia’s remote Pilbara

When space junk reenters the atmosphere, “what we tend to see is sort of like crackles and sparks,” Sayers said. “This is due to the fact that there is stuff burning up — so you’ve got solar panels going all over the place, you’ve got hunks of metal moving around.”

The fireball over Pilbara, on the other hand, glided smoothly through the sky. That makes it more likely to be a natural space object. The blue color, according to Nagle, indicates a high iron content. Many meteorites — space rocks that survive their fiery trip through Earth’s atmosphere — are high in iron. Some may be the cores of ancient asteroids, according to the Natural History Museum in the U.K.

Sayers said that the fireball looked similar to another spectacular meteor sighted in Australia in 2017. That 2017 fireball whooshed across the sky, but instead of hitting the ground or burning up in the atmosphere, it bounced back into space. The June 15 fireball may have been another grazing encounter, she told ABC News.

Meteors bright enough to be classified as fireballs are rare, but encounters with space rocks are common. According to NASA, about 48.5 tons (44,000 kilograms) of meteor material falls on Earth every day. Most space rocks disintegrate entirely or are the size of a pebble by the time they make it through Earth’s atmosphere. Occasionally, one makes a truly spectacular entrance: In February 2013, a meteor that would become known as the Chelyabinsk meteor entered the atmosphere over Russia and exploded in the biggest space blast since the 1908 Tunguska explosion. The explosion blew out windows in buildings in six different cities.

Originally published on Live Science.
By Stephanie Pappas – Live Science Contributor




3868: Astronomers solve whirling mystery around nearby black hole

How do you measure a black hole’s spin?

(Image: © Shutterstock)

Physicists may finally have figured out how fast a black hole visible in our Milky Way is spinning, and in doing so gotten closer than ever to figuring out everything there is to know about a certain class of these dark behemoths.

The singularity, named 4U1543-4, orbits a star about 24,700 light-years from Earth. It’s one of just a few similar objects that scientists have found in our region of space, and, at 9.4 times the mass of our sun, is not a supermassive black hole. Most physicists believe black holes, having crushed all their mass down to a single point, are identical except for three numbers: their mass, their charge and their spin. And while in theory a black hole could be very positively or negatively charged if it were made solely of electrons or protons, in the real world black holes (like all massive objects in the universe) probably have a net zero charge. Now, it seems like researchers have managed to make a pretty good measurement of this black hole’s spin.

Like anything in space, the compressed singularity hidden behind a black hole’s event horizon — the point beyond which not even light can escape — spins freely with all the momentum it’s picked up over the eons. But unlike with stars and planets, there’s no way to directly observe how fast the heavy point in space is spinning.

Related: 9 facts about black holes that will blow your mind

Instead, astronomers rely on proxies: the whirling clouds of matter just outside a black hole’s event horizon, which are tugged along by the singularity’s spin. By determining how fast that matter is moving, they can estimate the angular momentum, or spin, of the singularity itself.

Of course, being 24,700 light-years away these clouds of gas aren’t clearly visible. So astronomers don’t have the option of watching a speck of dust complete a circuit around the black hole’s event horizon. Instead, they measure the glow of X-rays produced close to the event horizon as the swirl of dust and gas surrounding the event horizon accelerates to extreme speeds. And that glow reveals how fast the gas and dust are moving, which in turn offers information about the singularity itself.

Two previous attempts to measure 4U1543-4’s spin led to wildly inconsistent results. This new approach relied on data from a particular flaring event, when the material around the black hole got much brighter, and also used improved techniques for calculating the spin.

Astronomers describe a black hole’s rate of spin with numbers between -1 and 1. A black hole not spinning at all has spin 0 a*, and black holes also have maximum spin speeds, which top out as they approach 1 a* or -1 a*.

As a black hole spins faster and faster, its event horizon shrinks closer and closer to the singularity, as UCLA astronomer Mark Morris told Universe Today in 2014. A black hole cannot spin so fast that its event horizon disappears and reveals the singularity.

This black hole, the researchers found, likely has a spin of 0.67. There are wide error bars around the estimate, which could top out at 0.82 or dip as low as 0.59. But regardless, the researchers wrote in their paper, its rate of spin is “moderate” for a black hole of this mass.

The paper describing these results was published March 5 in the journal Monthly Notices of the Royal Astronomical Society, and is available on arXiv.

Originally published on Live Science.
By Rafi Letzter – Staff Writer



BREAKING: Physicists announce first direct evidence for ‘axions’

This could be a game changer.

A team works on assembling the XENON1T dark matter experiment.
(Image: © XENON1T)

A team of physicists has made what might be the first-ever detection of an axion.

Axions are unconfirmed, hypothetical ultralight particles from beyond the Standard Model of particle physics, which describes the behavior of subatomic particles. Theoretical physicists first proposed the existence of axions in the 1970s in order to resolve problems in the math governing the strong force, which binds particles called quarks together. But axions have since become a popular explanation for dark matter, the mysterious substance that makes up 85% of the mass of the universe, yet emits no light.

If confirmed, it’s not yet certain whether these axions would in fact fix the asymmetries in the strong force. And they wouldn’t explain most of the missing mass in the universe, said Kai Martens, a physicist at the University of Tokyo who worked on the experiment. These axions, which appear to be streaming out of the sun, don’t act like the “cold dark matter” that physicists believe fills halos around galaxies. And they would be particles newly brought into being inside the sun, while the bulk of the cold dark matter out there appears to have existed unchanged for billions of years since the early universe.

Related: The 11 biggest unanswered questions about dark matter

And it’s not certain that axions were detected at all. Despite two years of data collection, the hint of a signal is still faint compared to what physics requires to announce the discovery of a new particle. Over time, as more data comes in, Martens told Live Science, it’s still possible that the evidence of a signal may fade away to nothing.

Still, it sure seems like there was a signal. It turned up in a dark underground tank of 3.5 tons (3.2 metric tons) of liquid xenon — the XENON1T experiment based at the Gran Sasso National Laboratory in Italy. At least two other physical effects could explain the XENON1T data. However, the researchers tested several theories and found that axions streaming out of our sun were the  likeliest  explanation for their results.

Physicists who weren’t involved in the experiment have not reviewed the data as of the announcement at 10 a.m. ET today (June 17). Reporters were briefed on the finding before the announcement, but data and paper on the find were not made available.

Live Science shared the XENON collaboration’s press release with two axion experts.

“If this bears out, and *if* is a big question, this is the biggest game changer in my corner of physics since the discovery of cosmic acceleration,” Chanda Prescod-Weinstein, a physicist at the University of New Hampshire who is not part of the collaboration, told Live Science in an email.

(The discovery of cosmic acceleration in 1998 showed that not only is the universe expanding, but that rate of expansion is getting faster.)

Related: The 18 biggest unsolved mysteries in physics

The XENON collaboration watches for tiny flashes of light in dark, insulated xenon tanks — of which XENON1T, operated between 2016 and 2018, is the largest example yet.

Shielded underground from most radiation sources, only a handful of particles (including dark matter) might make their way into the tank and collide with the atoms in the liquid within, stimulating those flashes. Most of those flashes are easy to explain, the results of interactions with particles physicists already know about. Despite the laboratory’s underground shielding, all sorts of particles make their way down there and account for most of what XENON detectors see. XENON researchers look for “excess” flashes, more flashes than you would predict based on known particle physics, that might suggest the existence of new particles.

This is the first time a XENON detector has actually detected an excess, a spike in activity at a low-energy range that matches what physicists would expect if solar axions do exist.

Until now, XENON results have partially ruled out another type of dark matter candidate, the “weakly interacting massive particles” (WIMPS). It didn’t detect enough flashes at the energy levels most WIMPs would produce to back up their existence, effectively ruling out most possible varieties of WIMP. But the experiments haven’t turned up any evidence for new particles before.

“Although the WIMP has been the dominant DM [dark matter] paradigm for many years, the axion has been around about as long, and recent years have seen a surge in experiments looking for axions,” said Tien-Tien Yu, a physicist at The University of Oregon, who also wasn’t involved in the XENON experiment.

So, if confirmed, the axion detection would fit neatly with recent developments in dark matter research (including older XENON data) that have made the once-popular WIMPs seem like long shots.

However, Yu told Live Science that it isn’t convincing on its own.

“It would be exciting if it were true, but I am skeptical as there could be some previously unconsidered source of background,” she said. (It’s also hard to evaluate the data without seeing it, she added.)

For instance, some radioactive source might have tripped XENON1T’s sensors in ways that mimic the expected patterns of solar axions interacting with liquid xenon.

Yu pointed out that there have been unconfirmed claims of dark matter particle discoveries before. And the “solar axions” that XENON may have found don’t appear to represent true cold dark matter (which would have originated in the early universe and be “cold”), but rather hot axions produced in our sun.

(Martens said this was true, but that solar axions — which would still be never-before-detected massive particles ghosting through the universe — would still count as dark matter in many respects. He acknowledged though that they wouldn’t explain that huge bulk of missing mass.)

The XENON collaboration itself proposed three possible explanations for the effect, which it described as an “excess” of events at low energies inside the tanks.

The best fit for the excess they saw, XENON said, was indeed solar axions. They expressed a “3.5 sigma” confidence in that hypothesis.

That means, Martens said, that there’s about a 2 in 10,000 chance that random background radiation produced the signal as opposed to solar axions themselves. Typically, physicists only announce a “discovery” of a new particle if the results reach 5 sigma significance, meaning a 1 in 3.5 million chance that the signal was produced by random fluctuations.

The other possibilities they considered were less convincing, but still worth taking seriously.

There might have been undetected traces of radioactive tritium (a version of hydrogen with two neutrons) in XENON1T, causing the surrounding liquid to sparkle. The XENON team worked hard to avoid this sort of noise from the beginning, Martens said. Still, he said, the tiny levels of tritium in question here would be impossible to perfectly screen out. And with XENON1T now taken apart to build a bigger future experiment, it’s impossible to go back and check.

The tritium hypothesis fits the data to a confidence level of 3.2 sigma. Joey Neilsen, a physicist at Villanova University in Pennsylvania, who is not involved in XENON, said that corresponds to about a 1 in 700 chance that random fluctuations would have produced the signal.

It’s also possible that neutrinos — faint, known particles from the sun that also stream through Earth — interact more strongly with magnetic fields than expected. If that’s true, according to a statement from the XENON collaboration, neutrinos could explain the signal they’re seeing. This hypothesis also comes with a 3.2 sigma confidence level, they wrote.

But even if  neutrinos explain XENON’s result, the Standard Model of particle physics would have to be rearranged to explain the unexpected neutrino behavior, Yu pointed out.

One telltale clue would suggest whether the solar axions hypothesis should be taken seriously: seasonal changes in the data, Yu said.

“If the signal were indeed from solar axions, one would expect a modulation in the signal due to the relative position of the sun to the Earth,” she said.

As our planet gets a bit more distant from the star it orbits, the solar axion stream should weaken. As Earth gets closer to the sun, Yu said, the signal should get stronger.

Martens said that no seasonal variation is visible in the XENON1T signal. The signal is too faint, and the experiment ran too briefly at just two years, for XENON1T to have picked it up.

Physicists will likely treat the XENON1T results as preliminary for the near future. An upcoming, larger XENON experiment called XENONnt, still under construction in Italy, should offer clearer statistics once completed, the team said. Further experiments underway or under construction in the United States and China will add to the existing data.

One hope, Martens said, is that seasonal variation will emerge from the data when the more sensitive XENONnt’s detector has finished its e 5-year run. That would strongly stack the deck in favor of solar axions, he said. And then all the international experiments might combine their raw xenon (drawing on a substantial chunk of the global supply) to build a 30-ton detector. Maybe then it will be possible to study this signal in detail (if it’s real) or detect other dark particles.

So these results are still preliminary. Still, Prescod-Weinstein said, there’s been plenty of buzz in the physics community in advance of the announcement.

“If this bears out, this is a big deal,” she wrote. “I’m hesitant to commentate on the strength of the data without having time to examine the results and discuss with peers. Of course I’d prefer a 5 sigma result!”

Editor’s note: This article was updated at 2:25 pm ET June 17 to reflect a clarification from Kai Martens. Martens said that while solar axions might not fix the asymmetry in the strong force, it’s also possible that they would fix that asymmetry.

Originally published on Live Science.
By Rafi Letzter – Staff Writer




3854: Are there really 36 alien civilizations out there? Well, maybe.

(Image: © Angela Harburn/Shutterstock)

How many intelligent alien civilizations are out there among the hundreds of billions of stars in the spiral arms of the Milky Way? According to a new calculation, the answer is 36.

That number assumes that life on Earth is more or less representative of the way that life evolves anywhere in the universe — on a rocky planet an appropriate distance away from a suitable star, after about 5 billion years. If that assumption is true, humanity may not exactly be alone in the galaxy, but any neighbors are probably too far away to ever meet.

Related: 9 strange, scientific excuses for why humans haven’t found aliens yet

On the other hand, that assumption that life everywhere will evolve on the same timeline as life on Earth is a huge one, said Seth Shostak, a senior astronomer at the SETI Institute in Mountain View, California, who was not involved in the new study. That means that the seeming precision of the calculations is misleading.

“If you relax those big, big assumptions, those numbers can be anything you want,” Shostak told Live Science.

Distant neighbors

The question of whether humans are alone in the universe is a complete unknown, of course. But in 1961, astronomer Frank Drake introduced a way to think about the odds. Known as the Drake equation, this formulation rounds up the variables that determine whether or not humans are likely to find (or be found by) intelligent extraterrestrials: The average rate of star formation per year in the galaxy, the fraction of those stars with planets, the fraction of those planets that form an ecosystem, and the even smaller fraction that develop life. Next comes the fraction of life-bearing planets that give rise to intelligent life, as opposed to, say, alien algae. That is further divided into the fraction of intelligent extraterrestrial life that develops communication detectable from space (humans fit into this category, as humanity has been communicating with radio waves for about a century).

The final variable is the average length of time that communicating alien civilizations last. The Milky Way is about 14 billion years old. If most intelligent, communicating civilizations last, say, a few hundred years at most, the chances that Earthlings will overlap with their communications is measly at best.

Solving the Drake equation isn’t possible, because the values of most of the variables are unknown. But University of Nottingham astrophysicist Christopher Conselice and his colleagues were interested in taking a stab at it with new data about star formation and the existence of exoplanets, or planets that circle other stars outside our own solar system. They published their findings June 15 in The Astrophysical Journal.

“This paper couldn’t have been written a few years ago,” Conselice told Live Science.

Related: Greetings, Earthlings! 8 ways aliens might contact us

The team calculated the age distribution of stars in the Milky Way, looking for those at least 5 billion years old and presumably old enough to host a humanlike civilization. They found that 97% of stars in the Milky Way are older than 5 billion years. Our solar system, at 4.5 billion years old, is a relative newbie in the galaxy, Conselice said, so it made sense that many stars in the Milky Way are older.

The researchers then calculated the number of those stars that are dense enough and stable enough to host planetary systems. A third of the stars older than 5 billion years qualified. Next, using what astronomers now know about the distribution of exoplanets, the researchers estimated the number of rocky planets within the habitable zones of those stars. They also calculated which stars are metal-rich enough to have orbiting rocky planets with the kind of elements you might need to construct, say, a radio transmitter. Finally, they set a lower limit of the life span of a communicating civilization at 100 years, based on Earth’s timeline with radio technology so far.

The result? If life on other planets follows the same trajectory as on Earth, there are 36 intelligent, communicating extraterrestrial civilizations sharing the Milky Way with humans today. There is uncertainty in this estimate, with a range from four other civilizations up to 211. If alien civilizations are likely to be distributed evenly throughout the Milky Way, our nearest neighbor would likely be 17,000 light-years away.

That means we’re quite unlikely to get in touch. The researchers calculate that a theoretical alien civilization would have to be broadcasting detectable signals for approximately 3,060 years for us to pick them up. That means to establish a two-way conversation with such a civilization, humanity (and the aliens) would have to hold it together for another 6,120 years.

Questioning assumptions

There are more optimistic scenarios for meeting ET. If, for example, life can evolve any time after 5 billion years, but not necessarily right at 5 billion years, the number of possible civilizations in the Milky Way rises to about 928. In this case, a civilization has to communicate for just 1,030 years to make contact.

Related: 13 ways to hunt intelligent aliens

The problem with these numbers is that the authors filled in some of the blanks in the Drake equation with astronomical data while dispensing with some of the most complicated, controversial variables without much discussion, Shostak said. Does life really evolve on any rocky planet within the habitable zone of a sun-like star? Does intelligent life really reliably show up about 4.5 billion years later? Had a chance asteroid not knocked Earth around 66 million years ago, killing off the dinosaurs, the timeline of the evolution of intelligent life on Earth could look quite different, after all. Perhaps the most limiting variable, Shostak said, is the assumption that a communicating civilization only transmits signals for a century. That seems pessimistic even for human civilization, which has its struggles but seems unlikely to stop using radio waves in the next couple of months, he said.

The answer to the Drake equation “depends a lot on the probability of life developing on a world and on [intelligent life] developing on a world and on the lifetime of intelligence,” Shostak told Live Science. “Those are all big things that could change the answer by an order of magnitude.”

Conselice said the calculations are a way of understanding humanity’s existence — and its future. If there turn out to be more civilizations out there in the galaxy than the new math predicts, that means that either life can evolve under far broader conditions than just Earth-like ones, or it means that civilizations tend to be far longer-lived than ours thus far.

“If we find a lot of them, that’s a good sign that we might have a very long lifetime for our civilization,” Conselice said.

On the other hand, if the search for extraterrestrial life continues to turn up empty, it could mean that life only rarely evolves, or that when civilization arises, it tends to self-destruct rapidly. Perhaps, the Milky Way was relatively bustling a few billion years ago, but those sparks of life have since gone out. In the end, Shostak said, there is only one way to find out.

“You’re only going to be able to write a paper in which you can make any estimate of how many alien societies there are once you find one or two,” Shostak said.

Originally published on Live Science.
By Stephanie Pappas – Live Science Contributor




3853: Weirdly-shaped wormholes might work better than spherical ones

Otherwise, they’d be ferociously unstable.

(Image: © Shutterstock)

Wormholes, or tunnels in the fabric of space-time, are ferociously unstable. As soon as even a single photon slips down the tunnel, the wormhole closes in a flash.

But what if the problem was that our imagined wormholes weren’t quite weird enough?

A new study suggests that the secret to a stable wormhole is making them funny looking. By shaping the wormhole so that it’s not a perfect sphere, we might be able to hold that tunnel open for long enough to travel through. The only catch is that said wormhole would have to be incomprehensibly tiny.

Down the hatch

Wormholes, if they exist, would allow you to travel from Point A to some extremely distant Point B without bothering with all the arduous traveling from Point A to Point B. They’re a shortcut. A cheat-code to the universe. See a star millions of light-years away? You could reach it in just a few minutes, if you had a wormhole linking you to that star.

No wonder it’s a staple of science fiction.

But wormholes aren’t just figments of our imagination designed to cut out all the boring parts of interstellar travel (which is most of it). They are born from the mathematics of Einstein’s general theory of relativity, our modern understanding of how gravity works. In that language, matter and energy bend and warp the fabric of space-time. In response, the bending and warping of space-time informs matter how to move.

Related: 8 ways you can see Einstein’s theory of relativity in real life

So when it comes to wormholes, you simply need to ask yourself: Is it possible to bend space-time in such a contorted way that it folds over on itself, forming a short-distance tunnel between two otherwise distant points?

The answer, discovered in the 1970’s, is a surprising yes. Wormholes are entirely possible and allowed within the framework of general relativity.

One catch: They tend to fall apart, immediately after they form.

The keys to stability

Wormholes are so unstable because, in essence, they consist of two black holes touching each other, connected at their singularities to form a tunnel.

But singularities are bad news: They are points of infinite densities. And they are surrounded by regions known as the event horizon, one-way barriers in the cosmos. If you cross a black hole’s event horizon, you’ll never escape.

In order to overcome this problem, the entrance to a wormhole must be outside of the event horizon. This way you can traverse the wormhole without plunging through an event horizon and never escaping.

But as soon as you enter such a wormhole, there’s simply too much mass hanging around, and the gravity of your presence distorts the wormhole tunnel, causing it to collapse in on itself, snapping shut like an overstretched rubber band, leaving behind two solitary black holes separated in space (and presumably bits of your corpse scattered across the observable universe).

Related: What if you fell into a black hole?

It turns out that there is a way to keep the wormhole entrance away from the event horizon and keep it stable enough for you to travel through. One catch: The solution requires the presence of a material with negative mass. Negative mass is just like normal mass, but with a minus sign. And if you collected enough negative mass together in a single spot, you could use it to hold open a wormhole.

But as far as we know, matter with negative mass doesn’t exist. We have no evidence for it, and if it did exist it would violate a lot of laws of the universe, like inertia and the conservation of momentum. For example, if you kicked a negative-mass ball, it would fly backward. If you put a negative-mass object next to a positive-mass object, instead of attracting, they would repel each other, instantly accelerating away from each other to infinity.

Since negative mass appears to be a no-go in the cosmos, at first glance it looks like wormholes are unlikely to exist in the universe as well.

A quantum of solace

But that story of wormholes relies on the mathematics of general relativity, which is, like I said, our current understanding of how gravity works.

That is, our current, incomplete understanding of how gravity works.

We know that general relativity doesn’t describe all the gravitational interactions in the universe, because it falls apart when gravity becomes very strong over small scales (like, say, the singularities inside of black holes). To solve those situations, we need to turn to a quantum theory of gravity, which would meld our understanding of the world of subatomic particles with our larger-scale understanding of gravity. And that, we don’t have, since every time we try to piece one together it falls apart into nonsense.

But still, we have some clues about how quantum gravity might work, and the more we learn, the more we can understand about the potential feasibility of wormholes. It could be that a new-and-improved understanding of gravity would reveal that you don’t need negative-mass matter at all, and that stable, traversable wormholes are A-OK.

A pair of theorists at Tehran University in Iran published a new investigation of wormholes to the preprint database arXiv. They applied some techniques that allowed them to study how quantum mechanics might alter the standard general relativity picture. They found that traversable wormholes might be allowed without negative-mass matter, but only if the entrances were stretched a little bit from pure spheres.

While the results are interesting, there is one catch. These hypothetical traversable wormholes are tiny. As in, extremely tiny. The wormholes would be at most 30% larger than the Planck length, or 1.61 x 10^minus 35 meters. And that means the traveler can’t be any bigger than that.

Oh, and the wormhole traveler has to be blazing along at nearly the speed of light.

While limited, the new research does open a tiny crack in the feasibility of wormholes that could be opened with further work. And then maybe TV show writers won’t have to gloss over any technicalities anymore.

Paul M. Sutter is an astrophysicist at SUNY Stony Brook and the Flatiron Institute, host of Ask a Spaceman and Space Radio, and author of Your Place in the Universe.

Originally published on Live Science.
y Paul Sutter – Astrophysicist




Einstein’s core idea about gravity just passed an extreme, whirling test in deep space

In this illustration, a pulsar (PSR J0337-1715) is shown with two white dwarf companions. The green mesh illustrates the curvature of space-time caused by the different masses. (Size and distances of the three components are not to scale.)
(Image: © Michael Kramer/MPIfR)

Once again, physicists have confirmed one of Albert Einstein’s core ideas about gravity — this time with the help of a neutron star flashing across space.

The new work makes an old idea even more certain: that heavy and light objects fall at the same rate. Einstein wasn’t the first person to realize this; there are contested accounts of Galileo Galilei demonstrating the principle by dropping weights off the Tower of Pisa in the 16th century. And suggestions of the idea appear in the work of the 12th-century philosopher Abu’l-Barakāt al-Baghdādī. This concept eventually made its way into Isaac Newton‘s model of physics, and then Einstein’s theory of general relativity as the gravitational “strong equivalence principle” (SEP). This new experiment demonstrates the truth of the SEP, using a falling neutron star, with more precision than ever.

The SEP has appeared to be true for a long time. You might have seen this video of Apollo astronauts dropping a feather and a hammer in the vacuum of the moon, showing that they fall at the same rate in lunar gravity.

But small tests in the relatively weak gravitational fields of Earth, the moon or the sun don’t really put the SEP through its paces, according to Sharon Morsink, an astrophysicist at the University of Alberta in Canada, who wasn’t involved in the new study.

“At some level, the majority of physicists believe that Einstein’s theory of gravity, called general relativity, is correct. However, that belief is mainly based on observations of phenomena taking place in regions of space with weak gravity, while Einstein’s theory of gravity is meant to explain phenomena taking place near really strong gravitational fields,” Morsink told Live Science. “Neutron stars and black holes are the objects that have the strongest known gravitational fields, so any test of gravity that involves these objects really test the heart of Einstein’s gravity theory.”

Neutron stars are the collapsed cores of dead stars. Super dense, but not dense enough to form black holes, they can pack masses greater than that of our sun into whirling spheres just a few miles wide.

The researchers focused on a type of neutron star called a pulsar, which from Earth’s perspective seems to flash as it spins. That flashing is a result of a bright spot on the star’s surface whirling in and out of view, 366 times per second. This spinning is regular enough to keep time by.

Related: 8 ways you can see Einstein’s theory of relativity in real life

This pulsar, known as J0337+1715, is special even among pulsars: It’s locked in a tight binary orbit with a white dwarf star. The two stars orbit each other as they circle a third star, also a white dwarf, just like Earth and the moon do as they circle the sun.

(Researchers have already shown that the SEP is true for orbits like this in our solar system: Earth and the moon are affected to exactly the same degree by the sun’s gravity, measurements suggest.)

The precise timekeeping of J0337+1715, combined with its relationship to those two gravity fields created by the two white dwarf stars, offers astronomers a unique opportunity to test the principle.

The pulsar is much heavier than the other two stars in the system. But the pulsar still falls toward each of them a little bit as they fall toward the pulsar’s larger mass. (The same thing happens with you and Earth. When you jump, you fall back toward the planet very quickly. But the planet falls toward you as well — very slowly, due to your own low gravity, but at the exact same rate as a feather or a hammer would if you ignore air resistance.) And because J0337+1715 is such a precise timekeeper, astronomers on Earth can track how the gravitational fields of the two stars affect the pulsar’s period.

To do so, the astronomers carefully timed the arrival of light from J0337+1715 using large radio telescopes, in particular the Nançay Radio Observatory in France. As the star moved around each of its neighbors — one in a quick little orbit and one in a longer, slower orbit — the pulsar got closer and farther from Earth. As the neutron star moved farther away from Earth, the light from its pulses had to travel longer distances to reach the telescope. So, to a tiny degree, the gaps between the pulses seemed to get longer.

As the pulsar swung back toward Earth, the gaps between the pulses got shorter. That allowed physicists to build a robust model of the neutron star’s movement through space, explaining precisely how it interacted with the gravity fields of its neighbors. Their work built on a technique used in an earlier paper, published in the journal Nature in 2018, to study the same system.

The new paper, published online June 10 in the journal Astronomy and Astrophysics, showed that the objects in this system behaved as Einstein’s theory predicts — or at least didn’t differ from Einstein’s predictions by more than 1.8 parts per million. That’s the absolute limit of the precision of their telescope data analysis. They reported 95% confidence in their findings.

Morsink, who uses X-ray data to study the mass, widths, and surface patterns of neutron stars, said that this confirmation isn’t surprising, but it is important for her research.

“In that work, we have to assume that Einstein’s theory of gravity is correct, since the data analysis is already very complex,” Morsink told Live Science in an in an email. “So tests of Einstein’s gravity using neutron stars really make me feel better about our assumption that Einstein’s theory describes the gravity of a neutron star correctly!”

Without understanding the SEP, Einstein would never have been able to develop his ideas of relativity. In an insight he described as “the most fortunate thought in my life,” he recognized that objects in free fall don’t feel the gravitational fields tugging on them.

(This is why astronauts in orbit around the Earth float. In constant free fall, they don’t experience the gravitational field that holds them in orbit. Without windows, they wouldn’t know Earth was there at all.)

Most of Einstein’s key insights about the universe begin with the universality of free fall. So, in this way, the cornerstone of general relativity has been made that much stronger.

Originally published on Live Science.

By Rafi Letzter – Staff Writer




3820: Why a physicist wants to build a particle collider on the moon

NASA recently launched the Commercial Lunar Payload Services (CLPS) initiative whose aim is to find the best future payloads to deliver to the surface of the moon. These payloads would include instruments for basic science investigations. Shown here, a Lockheed Martin space concept for a commercial lunar lander.
(Image: © NASA)

As we probe deeper into the innermost workings of the universe, our particle physics experiments have become ever more complex. In order to reveal the secrets of the tiniest subatomic particles, physicists must make colliders and detectors as cold as possible, remove as much air as possible, and keep them as still as possible to get reliable results.

So at least one physicist is asking: What if we just skipped all that and set up our particle physics experiments on the moon?

Related: 5 Strange, cool things we’ve recently learned about the moon

A proposal published to the preprint database arXiv earlier this year argues that the moon is actually a pretty decent place to do high-energy physics.

First, it’s cold. Very cold. With no atmosphere and no water, there’s nothing to transport the heat of sunlight from one place to another. At night, with the sun below the horizon, temperatures dip to minus 100 degrees Fahrenheit (minus 73 degrees Celsius) — in the range of typical cryogenic setups on Earth. In the daytime, things get a little bit hotter, reaching more than 100 F (38 C). But as the ice tucked away in the shadows of lunar craters proves, all you need to cool yourself down is a little bit of shade. Again, with no air or water, areas out of direct sunlight are blissfully cold.

Physicists need those cold temperatures for a few reasons. In accelerators, cold temperatures ensure that the superconducting magnets — used to fling the particles inside the accelerator to nearly the speed of light — don’t melt themselves. Second, the hotter a detector, the more noise you have to deal with in trying to tease out the tiny signals from subatomic particles. (More heat equals more molecules vibrating, which equals more noise.)

Besides the chilly temperatures, the fact that the moon has no atmosphere is also a major boon. Physicists have to pull all the air out of their accelerators and detectors — wouldn’t want your near-the-speed-of-light particles to slam into a wandering nitrogen molecule before you even get started. But the moon has a vacuum 10 times better than anything physicists have manufactured in their experiments. And it does it naturally, without any effort at all.

Lastly, because of tidal locking — meaning our satellite body takes the same amount of time to rotate about its axis (its rotational period) as it does to orbit Earth — the moon keeps the same face pointed toward Earth at all times. This means a lunar particle beam could be pointed back toward a detecting laboratory on Earth, taking advantage of the long distance without having to work very hard to align the setup.

Lunar neutrino factory

Perhaps, the most promising use of a lunar physics experiment would be as a source of neutrinos. Neutrinos are ghostly, nimble little particles that have no electric charge and hardly any mass at all. This enables them to flit through normal matter without hardly ever noticing — hundreds of billions of neutrinos are passing through your body right now, and you can’t feel a thing.

Related: The 18 biggest unsolved mysteries in physics

Needless to say, neutrinos are hard to study and understand. They’re made in copious quantities in nuclear reactions, so all it would take would be to stick a nuclear power plant on the moon and let it rip. The neutrinos that it produces would race to Earth, where we could pick them up and study them.

One aggravating and mysterious property of neutrinos is that they’re capable of changing types (or “flavors” in the physics jargon) as they fly. By having a long distance separating neutrino generation and detection, we give more neutrinos a chance to “change flavors,” and we can better understand this behavior. The moon makes a perfect source: It’s far enough away that we could get long distances, but close enough that we could capture neutrinos in sufficient quantities to actually study (and presumably also troubleshoot the facility if something goes wrong).

Who needs Earth anyway?

Neutrinos aren’t the only thing a facility on the moon could shoot at Earth. Even our most powerful particle colliders can’t come close to the energies that nature is capable of generating to launch particles (and if we’re being accurate, we can’t even come close to a billionth of those energies). Every second of every day, high-energy particles come screeching into our atmosphere, knocking over a few molecules and releasing a shower of particle byproducts before hitting the ground.

Known as cosmic rays, these particles come from some of the most energetic sources in the universe (think supernovas), but they are poorly understood. So what we could really use is a cosmic ray gun – something that manufactures them somewhere else and blasts them into our atmosphere so we can study them. How about … the moon? A facility on the moon could produce high-energy particles in great quantity, shoot them at our atmosphere, and let us observe the resulting showers from the ground, helping us better understand this high-energy side of the universe.

But why stop there? Why not just put the detectors on the moon too? A complete particle physics experiment, with source, accelerator and detector on the moon offers several advantages over Earth-based systems. The number-one bottleneck here is the need for a highly-controlled vacuum, which constricts Earth experiments to be relatively compact.

But on the moon, you get a vacuum for free. And that vacuum is much, much better than the one used in particle collider experiments. You could build your facility as big as your heart’s content, without once having to invest in a single air pump. That’s quite the advantage.

I suppose there’s the minor technical challenge of actually getting there and building sophisticated experiments on the moon, but once that’s solved physics could see a big, lunar-based boost.

Originally published on Live Science.
By Paul Sutter – Astrophysicist





3819: Mysterious deep-space flashes repeat every 157 days

The find could be a big clue about the nature of fast radio bursts.

An artist’s impression of a fast radio burst (FRB) reaching Earth, with colors signifying different wavelengths.
(Image: © Jingchuan Yu, Beijing Planetarium)

Astronomers have discovered an activity cycle in another fast radio burst, potentially unearthing a significant clue about these mysterious deep-space phenomena.

Fast radio bursts, or FRBs, are extragalactic flashes of light that pack a serious wallop, unleashing in a few milliseconds as much energy as Earth’s sun does in a century. Scientists first spotted an FRB in 2007, and the cause of these eruptions remains elusive nearly a decade and a half later; potential explanations range from merging superdense neutron stars to advanced alien civilizations.

More than 100 FRBs have been discovered to date, and most of them are one-offs, flaring up just a single time (as far as we know). In January of this year, astronomers reported that one member of the “repeater” class, called FRB 180916.J0158+65, appears to exhibit a 16-day activity cycle: It fires off bursts for a four-day stretch, goes quiet for 12 days and then starts all over again.

The FRB 180916 was the first known to erupt in such a periodic way. And now scientists have spotted another.

Researchers monitored the known repeater FRB 121102 with the Lovell Telescope, a 250-foot-wide (76 meters) radio dish at Jodrell Bank Observatory in England, over the course of five years. They found strong indications of a 157-day activity cycle; 121102 seems to flare up for 90 days and then go silent for 67, the team reported in a new study.

It’s unclear what’s behind such cyclic activity, though scientists do have a few ideas. For example, periodic flare-ups could be caused by a wobble in the rotational axis of a highly magnetized neutron star known as a magnetar. Or they could be linked to the orbital motions of a neutron star in a binary system.

The wobble effects are expected to manifest over the span of a few weeks, study team members said. So they seem compatible with FRB 180916’s 16-day cycle but not with that of FRB 121102, which is 10 times longer. But who knows? And there’s also no guarantee that the same phenomenon is driving the periodicity of both repeating FRBs.

“This exciting discovery highlights how little we know about the origin of FRBs,” study co-author Duncan Lorimer, the associate dean for research at West Virginia University, said in a statement. “Further observations of a larger number of FRBs will be needed in order to obtain a clearer picture about these periodic sources and elucidate their origin.”

The new study, which was led by Kaustubh Rajwade of the University of Manchester in England, was published online this evening (June 7; June 8 United Kingdom time) in the journal Monthly Notices of the Royal Astronomical Society. You can read a preprint of it for free at

Mike Wall is the author of “Out There” (Grand Central Publishing, 2018; illustrated by Karl Tate), a book about the search for alien life. Follow him on Twitter @michaeldwall. Follow us on Twitter @Spacedotcom or Facebook.

Live Science
By Mike Wall – Senior Writer





Get ready for the full ‘strawberry’ moon on Friday


(Image: © Shutterstock)

Friday’s full moon, also known as the strawberry moon, will light up the night sky in most of the Western Hemisphere (including North America), but that’s not the case the world over.

In much of the Eastern Hemisphere, the full moon on Friday (June 5) will showcase a penumbral lunar eclipse, meaning that the strawberry moon will appear dark and silvery.

For anyone bummed out about missing the penumbral lunar eclipse, just wait one month; on July 4, North America will get a chance to see a different penumbral lunar eclipse, according to, a sister site of Live Science.

Related: This amazing photo reveals a lunar eclipse like you’ve never seen it before

The moon’s exact moment of fullness happens at 3:12 p.m. EDT (19:12 UTC) on Friday, according to NASA. However, because the moon won’t be visible in North America at the point, your best bet is to gaze skyward at moonrise, when the slightly-less-full moon will begin its ascent at 8:23 p.m. EDT (shortly before sunset at 8:31 p.m. EDT), according to Travel and Leisure.

The strawberry moon is named for the relatively short strawberry growing season in northeastern North America; it’s a name recognized by most Algonquin tribes, the now-defunct Maine Farmer’s Almanac reported in the 1930s, according to NASA.

In fact, June is prime strawberry growing time for most of the United States, according to the food site Epicurious, which also pointed out that strawberries are a favorite, ranking sixth as the country’s most popular fruit. If you have a sweet tooth, go for wild strawberries, which tend to have sweeter, tangier flavors than the more firm, waterier store-bought ones, Live Science previously reported.

Other names for this full moon include the mead moon, honey moon, rose moon and LRO moon (for the Lunar Reconnaissance Orbiter, which was launched toward the moon June 18, 2009), according to NASA. Whatever you call it, this will be the last full moon of spring, before the summer solstice on June 20.

On the other side of the world, June’s full moon will feature a penumbral lunar eclipse. Those in the Southern Hemisphere, including Africa, Australia and Central and Southern Asia, will see the penumbral lunar eclipse in its entirety, while the eastern coast of South America will see the end of the penumbral eclipse at moonrise, according to

Related: Glitzy photos of a supermoon

There are three kinds of lunar eclipses, which can happen only during a full moon. During a total lunar eclipse, when the moon passes directly through Earth’s full shadow (or umbra), the moon appears blood-red, colored by the world’s sunrises and sunsets. During a partial lunar eclipse, the umbra darkens only part of the full moon, making a chunk of the moon appear darker than the rest.

For the penumbral lunar eclipse this Friday, the strawberry moon is dipping 57% into the penumbra, or outer shadow, of Earth, Travel and Leisure reported. The lunar show begins at 1:45 p.m. EDT (17:45 UTC), but to catch the maximum eclipse, tune in at 3:24 p.m. EDT (19:24 UTC), according to, which explained that “the moon is below the horizon during this eclipse, so it is not possible to view it in New York.” The penumbral eclipse ends 3 hours and 18 minutes later at 5:04 p.m. EDT (21:04 UTC).

The regions that will see all or part of the June 4-5 penumbral lunar eclipse. (Image credit: Fred Espenak/NASA)

To watch a live stream of the eclipse, tune into the Virtual Telescope, which will get a peek at part of the penumbral lunar eclipse as it rises over Rome.

The celestial show doesn’t end there. According to, “a solar eclipse always occurs about two weeks before or after a lunar eclipse.” In this case, the solar eclipse — when the moon is directly between the sun and Earth — will happen on June 21. But, just like the strawberry moon’s penumbral lunar eclipse, this eclipse won’t be visible in North America.

Originally published on Live Science.
By Laura Geggel – Associate Editor




3707: Space Force launches robotic X-37B space plane on new mystery mission


It’s the sixth flight of the clandestine space plane.

CAPE CANAVERAL, Fla. — The U.S. Space Force’s mysterious X-37B space plane successfully launched on its sixth mystery mission from Florida today (May 17).

Riding atop a United Launch Alliance Atlas V rocket, the clandestine craft blasted off from Space Launch Complex 41 at Cape Canaveral Air Force Station here at 9:14 a.m. EDT (1314 GMT).

The on-time liftoff occurred just 24-hours after poor weather conditions at the Florida launch site forced ULA to scrub its original launch attempt, Saturday morning.

While the X-37B’s exact purpose is a secret, Space Force officials have revealed that the craft is packing numerous experiments on this trip to test out different systems in space. Some of those experiments include a small satellite called FalconSat-8, two NASA payloads designed to study the effects of radiation on different materials as well as seeds to grow food, and a power-beaming experiment using microwave energy.

Related: The X-37B space plane: 6 surprising facts

(Image credit: United Launch Alliance)

(Image credit: United Launch Alliance)

The U.S.Space Force and Air Force Rapid Response Capabilities Office have two of the miniature shuttle-like X-37B space planes (also known as Orbital Test Vehicles, or OTVs) that it uses for classified military missions in low-Earth orbit. They have flown five missions since 2010, four of them on ULA Atlas V rockets and the fifth on a SpaceX Falcon 9.

X-37B returns to space

Today’s launch occurred just six months after the most recent mission, OTV-5, landed at NASA’s Kennedy Space Center in Florida on Oct. 2, 2019, completing a record-setting 780 days (just over two years) sojourn in space.

Boeing built the X-37B space planes for the U.S. Air Force. The two vehicles have spent more than seven years in orbit across their missions. (Command of the mission and other space related activities transferred to the Space Force after its creation in 2019.)

Space Force officials have said that the experiments and technology the X-37B carries “enables the U.S. to more efficiently and effectively develop space capabilities necessary to maintain superiority in the space domain.”

Related: How the secretive X-37B space plane works (infographic)

The X-37B space plane ahead is seen tucked inside the payload fairing of its Atlas V rocket ahead of a May 17, 2020 launch. (Image credit: Boeing/US Space Force)

To that end, this mission will have even more experiments than previous flights. That’s thanks to the addition of a new service module — a cylindrical extension attached to the bottom of the craft — a first for this mission. The addition of a service module will help to increase the vehicle’s capabilities, enabling it to conduct more experiments and test new technologies throughout the mission, Space Force officials have said.

ULA launched the X-37B on an Atlas V rocket in the 501 configuration, which means the vehicle has a 17-foot (5 meters) wide payload fairing, a single engine Centaur upper stage, and no solid rocket boosters.

It marked the 84th flight of the Atlas V, which was recently dethroned as the most flown American launcher. That superlative was snagged by SpaceX’s Falcon 9 rocket, which became the world’s most flown booster in April and is also set to launch its next flight (a Starlink satellite fleet launch) early Tuesday, May 19.

Honoring coronavirus responders

The U.S. Space Force and United Launch Alliance dedicated the X-37B space plane’s OTV_6 launch to the first-responders and victims of the COVID-19 pandemic. (Image credit: United Launch Alliance)

Saturday’s launch, dubbed USSF-7, is dedicated to the first responders and medical personnel across the country who work daily to combat the ongoing coronavirus pandemic.

The mission is part of the military’s “America Strong” campaign, which also includes a series of flyovers by the Air Force Thunderbirds and Navy Blue Angels. ULA also stamped a tribute on the side of the Atlas V rocket that says: “In memory of COVID-19 victims and tribute to all first responders and front-line workers.”

COVID-19, the disease caused by the new coronavirus, has infected approximately 4.5 million people globally, with 1.45 million of them in the United States. At least 87,991 have died from the disease in the U.S. as of May 16, according to Livescience.

“Thank you for your courage in caring for the sick and keeping us safe,” ULA CEO Tory Bruno tweeted, addressing the many first responders working selflessly to support the nation in this difficult time.

“There are still heroes in this world,” he added.

Officials at the 45th Space Wing said they have been doing their part to make sure the launch went smoothly while simultaneously protecting its workforce.

“We have an obligation to keep space capabilities up and running for our nation,” Gen. John Raymond, chief of space operations in the U.S. Space Force and commander of the U.S. Space Command said during a prelaunch talk on May 6.

To that end, the 45th Space Wing has been rotating crews between launches, reduced on-site staff as much as possible and practiced social distancing. Both NASA’s Kennedy Space Center and the nearby Cape Canaveral Air Force Station have kept public viewing areas closed for this launch as well as a SpaceX launch scheduled for Sunday morning.

This mission marks the second national security launch under the Space Force since its establishment in December. (The first was the AEHF-6 military communications satellite launch in March.)

The X-37B space plane is about 29 feet (8.8 meters) long and resembles a miniature space shuttle. For OTV_6, the robotic spacecraft carried a new service module that supports more experiments and longer stays in space. (Image credit: U.S. Air Force)

Space Force officials have chosen to delay some of the planned missions, however, due to concerns about the pandemic. For instance, the next GPS navigation satellite mission GPS 3 SV03 has been delayed several months to no earlier than June 30 to ensure that ground control crews were able to stay safe.

It’s a busy time on the space coast, and the GPS constellation is healthy which reduces the pressure to get newer, upgraded satellites into orbit, officials said.

Today’s mission was originally part of a launch double header from Florida’s Space Coast.

Following the Atlas V launch, a SpaceX Falcon 9 rocket was supposed to take to the skies less than 24 hours later, carrying another batch of SpaceX’s Starlink satellites into orbit.

That launch was originally on the books for today, but weather delays at the launch site and the emergence of a tropical depression out in the Atlantic prompted SpaceX to move the launch date.

When the Falcon 9 does launch, it will bring the total number of Starlink internet satellites up to nearly 500. SpaceX CEO Elon Musk has said that between 400-800 satellites are needed to begin rolling out the first, albeit limited, iteration of its global internet service.

If all goes as planned, the Falcon 9 will lift off from Space Launch Complex 40 at 3:10 a.m. EDT (0710 GMT) on Tuesday.

Follow Amy Thompson on Twitter @astrogingersnap. Follow us on Twitter @Spacedotcom or Facebook.

By Amy Thompson – Contributor




3671: These lava tubes could be the safest place for explorers to live on Mars


The Martian surface is a radiation hot zone. But these lava tubes might offer safety.

Curiosity can handle the harsh radiation on the Martian surface. But people can’t.
(Image: © NASA/JPL/MSSS/Marco Di Lorenzo/Ken Kremer)

There’s no safe place to camp out on Mars. But a team of researchers has identified what could be future Martian explorers’ best possible hideout: a string of lava tubes in the low-lying Hellas Planitia — an impact basin blasted into the Red Planet’s surface by ancient meteor impacts.

Every part of Mars could kill you. Its surface is arid, starved of oxygen and blasted daily with unrelenting, unfiltered solar radiation. Any future Martian explorers will put their lives in peril when they embark. NASA has decades of experience hauling oxygen, food and water beyond Earth. But that last killer, the radiation, is a harder problem to tackle.

On Earth, a powerful magnetic shield, known as the magnetosphere, protects us from the harsh radiation of space. Without it, a constant stream of electromagnetic rays would damage our cells and DNA, with dire consequences to our health. Ionized particles, streaming through space as slower-moving solar wind or relativistic cosmic rays add to that risk. And we know from the experiences of the only humans to exit the magnetosphere — Apollo astronauts — that even a few days’ exposure to those particles can trigger headaches, flashes of light and cataracts, the researchers of the new study noted in their new paper. Plus, there’s always the risk that a solar flare or cosmic ray burst could expose a Martian habitat to a sudden, deadly dose.

Related: Here’s what NASA’s Opportunity rover saw before ‘lights out’

There’s only so much shielding you can put on a spacecraft or habitat, and even astronauts on the International Space Station accept much higher cancer risk than they would experience on Earth, NASA has said. But in the new paper, that team of researchers argues that the Hellas Planitia lava tubes might be among the safest places for Martian explorers to camp out.

Hellas Planitia offers a few protective advantages on its own: NASA probes have shown that the most intense radiation environments on Mars are at the poles. But Hellas Planitia lies closer to the equator. And of all Martian environments, the impact basin is among the most low-lying at about 23,464 feet (7,152 meters) deep. That means more of Mars’ thin atmosphere overhead. About 50% less radiation reaches the basin floor than higher-elevation regions of Mars, the researchers wrote. Explorers could expect about 342 microsieverts per day (a unit of radiation exposure) in the basin, compared with 547 μSv/day elsewhere on Mars. That’s a much smaller dose, but still much higher than what’s typically considered safe.

The precise effects of long-term exposure to sub-fatal doses of radiation like this aren’t well understood, as Richard Kerr wrote for the news section of the journal Science in 2013. But 342 μSv/day is 25% higher than what the average astronauts experience on the ISS every day, where NASA typically limits exposures to just a couple months. Martian explorers might spend years on the Red Planet. And exposure to such a high dose for years on end could pose a serious danger to everyone involved, the researchers said. (The maximum safe radiation dose, according to the United States Nuclear Regulatory Commission is 620 millirem, or 6,200 μSv, per year. At 342 μSv/day, Martian explorers would experience that much radiation in just 19 days.)

In the northeast corner of Hellas Planitia lies the Hadriacus Mons. This mountain formed as a result of an erupting volcano back when lava still flowed in the long-since-cooled Martian interior.

On Earth, lava flows can burrow through the ground on their way to the surface, leaving behind empty tunnels with hardened walls, floors and ceilings once the molten rock drains away. You can spot signs of them flying overhead: A line of “pit craters” near a dormant volcano tells the story of a lava tube that formed, drained and then partially collapsed in one section or another — sometimes even leaving behind “skylight” holes in the middle of the crater, the researchers wrote.

Hunting through images taken from probes in Mars’ orbit, the researchers identified several such pit crater chains and other evidence of old lava flows that burrowed into the Martian crust around Hadriacus Mons. Multiple sites around that low-lying mountain seem like tempting candidates for future exploration, they wrote. And on Mars, with its lower gravity, simulations suggest that the hollowed-out tubes would be much larger than those found on Earth.

An image shows aerial views of a pit crater chain hiding a lava tube in New Mexico (top) and a similar formation on Mars (bottom). (Image credit: Paris et al./arXiv)

Assuming these clues point to the existence of real lava tubes in Hellas Planitia, the researchers visited similar sites in the American Southwest to test the idea of lava tubes as radiation shields. Though cosmic radiation on Earth’s surface is much lower than on Mars, some of those particles do make it to our planet’s surface. Comparing measurements of radiation inside and outside California’s Mojave Aiken tube, Arizona’s Lava River Cave, and New Mexico’s Big Skylight, Giant Ice Cave and Junction Cave, the researchers found a significant radiation-shielding effect. Extrapolating their results to Mars, they calculated that living in a Hellas lava tube, people might experience just about 61.64 μSv/day. That’s still high, but closer to what you could expect if you got your teeth X-rayed several times a day than what you could expect living in a habitat on the surface of Mars.

There are other potential advantages to life in the tubes, the researchers wrote. Shore them up, seal them off, and it might be possible to pressurize them and warm them up to create livable environments much larger than what a rocket could haul from Earth. Like human-made shelters, the tubes would also offer protection from micrometeorites, temperature fluctuations and potentially dangerous substances in the Martian surface dust.

And these explorers could learn more about the Red Planet. “The candidate lava tubes, moreover, can serve as important locations for direct observation and study of Martian geology and geomorphology,” the researchers concluded, “as well as potentially uncovering any evidence for the development of microbial life early in the natural history of Mars.”

The paper has been accepted for publication in The Journal of The Washington Academy of Sciences and can be read on arXiv.

Originally published on Live Science.
By Rafi Letzter – Staff Writer



3620: A long-lost type of dark matter may resolve the biggest disagreement in physics


This stuff would have existed for thousands of years before disappearing.

A map of the sky shows the Cosmic Microwave Background (CMB), a remnant of the period of the early universe when this lost dark matter might have existed.
(Image: © ESA and the Planck Collaboration)

One of the deepest mysteries in physics, known as the Hubble tension, could be explained by a long-since vanished form of dark matter.

The Hubble tension, as Live Science has previously reported, refers to a growing contradiction in physics: The universe is expanding, but different measurements produce different results for precisely how fast that is happening. Physicists explain the expansion rate with a number, known as the Hubble constant (H0). H0 describes an engine of sorts that’s driving things apart over vast distances across the universe. According to Hubble’s Law (where the constant originated), the farther away something is from us, the faster it’s moving.

And there are two main ways of calculating H0. You can study the stars and galaxies we can see, and directly measure how fast they’re moving away. Or you can study the cosmic microwave background (CMB), an afterglow of the Big Bang that fills the entire universe, and encodes key information about its expansion.

Related: The 11 Biggest Unanswered Questions About Dark Matter

As the tools for performing each of these measurements have gotten more precise, however, it’s become clear that CMB measurement and direct measurements of our local universe produce incompatible answers.

Researchers have offered different explanations for the disparity, from problems with the measurements themselves to the possibility we live in a low-density “bubble” within the larger universe. Now, a team of physicists is suggesting that the universe might have fundamentally changed between the time after the Big Bang and today. If an ancient form of dark matter decayed out of existence, that loss would have changed the mass of the universe; and with less mass, there would be less gravity holding the universe together, which would have impact the speed at which the universe expands — leading to the contradiction between the CMB and the direct measurements of the universe’s expansion rate.

A warm component

There was a time, decades ago, when physicists suspected dark matter might be “hot” — zipping around the universe at close to the speed of light, said Dan Hooper, head of the Theoretical Astrophysics Group at the Fermi National Accelerator Laboratory in Batavia, Illinois, and co-author of the new paper. But by the mid-1980s they were convinced that this unseen stuff that makes up most of the mass of the universe is likely slower-moving and “cold.” Physicists refer to the mostly widely-accepted model of the universe as Lambda-CDM, for “Cold Dark Matter.”

Still, Hooper told Live Science, the idea of “warm” dark matter — a form of dark matter that falls somewhere in between the hot and cold models — still gets some traction in the physics world. Some physicists speculate that dark matter is made of “sterile neutrinos,” for example, theoretical ghostly particles that barely interact with matter. This hypothetical dark matter would be much warmer than typical Lambda-CDM models allow, but not hot.

“Another possibility is that most of the dark matter is cold, but maybe some of it is warm. And in our paper, the stuff that’s warm isn’t even stuff that’s around today. It’s stuff that was created in the early universe and after thousands or tens of thousands of years it started to decay. It’s all gone by now,” Hooper said.

Related: 11 fascinating facts about our Milky Way galaxy

That lost dark matter’s mass would have represented a significant chunk of the total mass of the universe when it existed, leading to a different expansion rate when the CMB formed just after the Big Bang. Now, billions of years later, it would be long gone. And all the stars and galaxies we can measure would be moving away from us at speeds determined by the universe’s current mass.

“When you measure the local Hubble constant you’re really measuring that thing: You’re measuring how fast things are moving apart from one another, you’re measuring how fast space is expanding,” Hooper said. But translating the CMB data into an expansion rate requires using a model, such as the Lambda-CDM. “So if you get different measurements from the local measurements and the CMB measurement, maybe that model’s wrong.”

Local measurements — measurements of the region of space close enough to Earth for astronomers to precisely measure the speed and distance of individual objects — don’t require cosmological models to interpret, so they’re typically seen as more straightforward and robust.

Some researchers have still suggested there may be problems with our measurements of the local universe. But most attempts to resolve the Hubble tension involve tweaking Lambda-CDM somehow. Usually, they add something to the model that changes how the universe expands or evolves. This paper, Hooper said, is another step down that road.

“I’m not going to give the impression that it makes everything great,” he said. “It’s not a perfect concordance among the data by any means. But it makes the tension less severe — I don’t know of any solution to this, other than ‘the measurements are wrong,’ that reduces the tension [as much as you’d need to fully solve the problem].”

Dark Radiation

Hooper’s original proposal to his collaborators on the paper didn’t involve warm dark matter at all, he said. Instead, he imagined a second, lost form of cold dark matter. But when they started to test that idea, he said, they found that this extra cold dark matter was screwing up the whole structure of the universe. Stars and galaxies formed in ways that didn’t match what we see around us in the universe today. The decayed, lost form of dark matter, they concluded, had to be warm if it was going to fit observations.

The new paper doesn’t determine what particles the lost dark matter might be made of, but strongly suggests that warm dark matter might have been made up of sterile neutrinos — particles that other physicists also believe are likely out there.

“It’s definitely the thing that requires the fewest number of tooth fairies to make work,” Hooper said. “But other possibilities exist.”

Whatever it is though, it must have turned into something even more exotic and feebly interacting when it decayed. Matter can’t just stop existing; it has to transform into something else. If that something else were distributed differently through the universe, or interacted differently with other particles in the universe, that would change how the universe expanded.

“So we’d be surrounded in a bath of this dark radiation,” Hooper said. “We’re already surrounded in a bath of neutrinos so this would just be a little bit more of that kind of stuff. Some sort of bath that fills the universe today of very, very inert forms of matter.”

For now, researchers don’t have methods for probing the for this sort of hidden radiation, Hooper said, so the idea remains speculative. The paper was published to the arXiv database April 13.

Originally published on Live Science.
By Rafi Letzter – Staff Writer




Black hole bends escaping light ‘like a boomerang’


Even light can’t resist the pull of these irresistible cosmic objects.

(Image: © ESO/L. Calçada)

Light escaping from a black hole may “boomerang” its way to freedom, new X-ray images reveal.

Researchers found this odd behavior while reviewing archival X-ray observations of a black hole that’s approximately 10 times as massive as our sun. Located about 17,000 light-years from Earth, the black hole siphons material from a partner star; together, the black hole and star are known as XTE J1550-564.

Things can get pretty weird around a black hole. These exceptionally dense cosmic objects exert such a powerful gravitational pull that even light can’t resist their attraction. And scientists recently found that light behaves even more strangely around a black hole than once thought. Light in a black hole’s accretion disk — a spiraling, flattened cloud of dust and gas that circles the edges of a black hole — can sometimes escape into space. But the departing light from the XTE J1550-564 black hole didn’t follow the predictable path. Instead of escaping directly from the disk, the light was instead pulled back toward the black hole and then reflected off the disk and away from the black hole “like a boomerang,” researchers reported in a new study.

Related: Stephen Hawking’s most far-out ideas about black holes

They modeled the black hole’s accretion disk and its corona — a lower-density gas zone very close to the black hole — using data captured by the Rossi X-ray Timing Explorer, a now-defunct NASA satellite mission that investigated black holes, neutron stars and other X-ray emitting objects between 1995 and 2012.

“Typically, what we study is light that comes from that gas” — the corona — “and it bounces off of this disk that’s spiraling toward the black hole,” said lead study author Riley Connors, a postdoctoral researcher in physics at the California Institute of Technology’s Cahill Center for Astronomy and Astrophysics in Pasadena, California.

Normally, the team studies light “coming from that corona and hitting the disk, bouncing off, and then arriving at our telescopes. That’s something we’ve been studying for a long time,” Connors told Live Science.

This time, however, some of the light bouncing off the black hole’s disk appeared to originate in the disk itself rather than in the corona; it was then dragged back toward the black hole before bouncing away.

“The thing that we found, that was predicted in the 1970s, is that you could see light that comes from the disk bent all the way back onto itself,” Connors said.

Light from different regions around the black hole has distinctive X-ray signatures that tell scientists where the light came from. When the study authors looked at the data for XTE J1550-564, they saw light that was reflected from the black hole but had emission “fingerprints” that didn’t quite match those in light that came from the corona, Connors said. The researchers then turned to computer models to explain the anomaly.

This illustration shows how some of the light coming from a disk around a black hole is bent back onto the disk itself due to the gravity of the black hole; the light is then reflected back off the disk. (Image credit: NASA/JPL-Caltech/R. Hurt (IPAC)/R. Connors (Caltech))

Putting a new spin on black holes

This discovery could help scientists confirm other elusive aspects of black holes, such as how fast they spin. Researchers already understand how an accretion disk around a black hole behaves. By adding this boomeranging light to their computer models, astrophysicists can then calculate a black hole’s rotation speed based on how much of the light is bending and bouncing back, Connors explained.

“It’s perhaps a more reliable way for us to measure how fast the black holes are spinning,” he said. ‘”

Though this phenomenon has been documented to date only in the XTE J1550-564 system, this is likely not the only black hole where light performs these unusual gymnastic feats, Connors said.

“We’re starting to look at data from other black holes; we have data from multiple X-ray satellites for dozens of these systems in our own galaxy,” he said. “We think that we should see this in many other sources.”

The findings were published online March 20 in The Astrophysical Journal.

Originally published on Live Science.
By Mindy Weisberger – Senior Writer




North Pole’s largest-ever ozone hole finally closes


An unusually strong polar vortex kept the hole open for nearly a month — now, it’s finally shut again.

Ozone-rich air (red) floods the atmosphere over the North Pole on April 23, closing the single largest ozone hole ever detected in the Arctic.
(Image: © Copernicus Atmosphere Monitoring Service)

After looming above the Arctic for nearly a month, the single largest ozone hole ever detected over the North Pole has finally closed, researchers from the European Union’s Copernicus Atmosphere Monitoring Service (CAMS) reported.

“The unprecedented 2020 Northern Hemisphere ozone hole has come to an end,” CAMS researchers tweeted on April 23.

The hole in the ozone layer — a portion of Earth’s atmosphere that shields the planet from ultraviolet radiation — first opened over the Arctic in late March when unusual wind conditions trapped frigid air over the North Pole for several weeks in a row.

Those winds, known as a polar vortex, created a circular cage of cold air that led to the formation of high-altitude clouds in the region. The clouds mixed with man-made pollutants like chlorine and bromine, eating away at the surrounding ozone gas until a massive hole roughly three times the size of Greenland opened in the atmosphere, according to a statement from the European Space Agency (ESA).

Related: 16 times Antarctica revealed its awesomeness in 2019

While a large ozone hole opens every autumn over the South Pole, the conditions that allow these holes to form are much rarer in the Northern Hemisphere, the ESA researchers said. The Arctic ozone hole opened this year only because the cold air was concentrated in the area for much longer than is typical.

Copernicus ECMWF @CopernicusECMWF

The unprecedented 2020 northern hemisphere #OzoneHole has come to an end. The #PolarVortex split, allowing #ozone-rich air into the Arctic, closely matching last week’s forecast from the #CopernicusAtmosphere Monitoring Service.

More on the NH Ozone hole 

Late last week, that polar vortex “split,” the CAMS researchers said, creating a pathway for ozone-rich air to rush back into the area above the North Pole.

For now, there’s far too little data to say whether Arctic ozone holes like this one represent a new trend. “From my point of view, this is the first time you can speak about a real ozone hole in the Arctic,” Martin Dameris, an atmospheric scientist at the German Aerospace Center, told Nature.

Meanwhile, the annual Antarctic ozone hole, which has existed for roughly four decades, will remain a seasonal reality for the foreseeable future. Scientists are optimistic that the hole may be starting to close; a 2018 assessment by the World Meteorological Organization found that the southern ozone hole has been shrinking by about 1% to 3% per decade since 2000 — however, it likely won’t heal completely until at least 2050. Warmer Antarctic temperatures caused by global warming are partially responsible for the hole’s apparent shrinkage, but credit is also due to the Montreal Protocol, a global ban on ozone-depleting pollutants enacted in 1987.

Originally published on Live Science.
By Brandon Specktor – Senior Writer




‘UFO’ videos declassified by US Navy


Three videos show unidentified aircraft flying at hypersonic speeds

U.S. Navy videos of alleged UFO sightings were previously available but had not been officially declassified. (Image: © U.S. Navy)

Three videos of midair military interactions with UFOs, previously released without official permission by a UFO research group, were declassified and shared online today (April 27) by the U.S. Navy.

The footage, captured by U.S. Navy pilots years ago, shows mysterious, wingless aircraft traveling at hypersonic speeds, with no visible means of propulsion. UFO research group To the Stars Academy of Arts and Science published the clips in 2017 and 2018; at the time, those videos were allegedly declassified, Live Science previously reported. However, in September 2019, Joseph Gradisher, a spokesperson for the Deputy Chief of Naval Operations for Information Warfare said that the footage had not been cleared for official release.

Today, the three clips — “FLIR,” “GOFAST” and “GIMBAL” — appeared for the first time on the Naval Air Systems Command website, available to download through the Freedom of Information Act.

Related: Flying saucers to mind control: 22 declassified military & CIA secrets

In releasing the videos, the U.S. Navy officially acknowledges that its pilots encountered so-called unidentified aerial phenomena, according to the military news website

The three sightings, which took place in November 2004 and in January 2015, were recorded by F/A-18 Hornet fighter pilots during military training exercises in restricted airspace. Unlike fighter jets, the airborne enigmas had “no distinct wing, no distinct tail, no distinct exhaust plume,” Navy pilot Lt. Danny Accoin said in the 2019 History Channel documentary series “Unidentified: Inside America’s UFO Investigation.”

Department of Defense officials decided to release the videos after determining that the footage “does not reveal any sensitive capabilities or systems, and does not impinge on any subsequent investigations of military air space incursions by unidentified aerial phenomena,” Pentagon spokesperson Sue Gough said in a statement.

To the Stars Academy, founded by former Blink-182 singer Tom DeLonge, shared the Flir and Gimbal clips in December 2017, and shared GoFast in March 2018. Though a video description claimed that all three clips had “been through the official declassification review process of the United States government and approved for public release,” the footage had not been properly declassified and should not have been shared publicly, Gradisher said in 2019.

There is as yet no explanation or identification — official or not — for the mysterious aircraft that the pilots recorded.

Originally published on Live Science.
By Mindy Weisberger – Senior Writer




3613: Big asteroid shows itself ahead of Earth flyby on April 29


We have nothing to fear from 1998 OR2.

The Arecibo Observatory captured this radar image of the big asteroid 1998 OR2 on April 18, 2020. 1998 OR2 will fly by Earth at a distance of 3.9 million miles (6.3 million kilometers) on April 29.
(Image: © Arecibo Observatory/NASA/NSF)

We’ve now got a good visual on the big space rock that’s going to fly by Earth next week.

On Saturday (April 18), the Arecibo Observatory in Puerto Rico captured a radar image of the asteroid 1998 OR2, which will zoom within 3.9 million miles (6.3 million kilometers) of our planet on April 29.

For perspective: The moon orbits Earth at an average distance of about 239,000 miles (385,000 km). So we have nothing to fear from asteroid 1998 OR2’s Earth flyby on April 29, scientists stress.

Related: Potentially dangerous asteroids (images)

Arecibo team members have been wearing masks in the workplace to help minimize the spread of the novel coronavirus, and they apparently see a bit of themselves in the approaching space rock.

“#TeamRadar and the @NAICobservatory staff are taking the proper safety measures as we continue observations. This week we have been observing near-Earth asteroid 1998 OR2, which looks like it’s wearing a mask! It’s at least 1.5 km across and is passing 16 lunar distances away!” team members tweeted on Saturday via the @AreciboRadar account. (@AreciboRadar is not an official Arecibo account. But @NAICobservatory is, and it retweeted the April 18 post.)

Arecibo Radar @AreciboRadar

#TeamRadar and the @NAICobservatory staff are taking the proper safety measures as we continue observations. This week we have been observing near-Earth asteroid 1998 OR2, which looks like it’s wearing a mask! It’s at least 1.5 km across and is passing 16 lunar distances away!

The Arecibo researchers aren’t the only ones keeping an eye on 1998 OR2. For example, Italian astrophysicist Gianluca Masi, who runs the online Virtual Telescope Project, has been tracking the asteroid as well.

And Masi will continue to do so. On April 28, in fact, he will host a live webcast about 1998 OR2 that will feature telescope views of the object.

Astronomers estimate that 1998 OR2 is between 1.1 and 2.5 miles (1.8 to 4.1 kilometers) wide — big enough that an impact could threaten human civilization. But, to repeat, there is nothing to fear here; the asteroid will miss us by a large margin on April 29.

Indeed, you should quell any general death-from-above fears that may be running rampant in your head. NASA has found and tracked the vast majority of giant near-Earth asteroids, and none of them pose a threat to Earth for the foreseeable future.

Mike Wall is the author of “” (Grand Central Publishing, 2018; illustrated by Karl Tate), a book about the search for alien life. Follow him on Twitter @michaeldwall. Follow us on Twitter @Spacedotcom or Facebook

By Mike Wall – Senior Writer