NASA says there are probably organic salts on Mars

NASA has been studying Mars for a long time now. Scientists working with the various rovers that have been sent to the Martian surface have uncovered plenty of interesting things, but evidence supporting the theory that there was once life on the Red Planet is still elusive. Finding organic molecules could go a long way toward changing that, so news that a team of NASA researchers now believes that organic salts are almost certainly present on Mars is pretty exciting… but there’s a catch.

 NASA explains that a group of scientists believe they’ve discovered indirect evidence of organic salts on Mars in samples collected by NASA’s own Curiosity rover. The rover’s Sample Analysis at Mars (SAM) automated chemistry lab returned data that hints at Martian salts, but known where those salts came from is another matter entirely.

Organic molecules on Mars could be a sign that life once existed there. It would be a monumental discovery, of course, but simply finding this “smoking gun,” as it were, isn’t proof enough to make a declaration. There are certain geological processes that can also generate organic molecules, and these can happen in the complete absence of life. It complicates the discoveries quite a bit, but if these salts are found it’ll be vital that NASA focus on the regions where they are if they hope to uncover hard evidence of life.

“If we determine that there are organic salts concentrated anywhere on Mars, we’ll want to investigate those regions further, and ideally drill deeper below the surface where organic matter could be better preserved,” James M. T. Lewis of NASA’s Goddard Space Flight Center said in a statement. Lewis led the research into the possible presence of salts on Mars. “We’re trying to unravel billions of years of organic chemistry and in that organic record there could be the ultimate prize: evidence that life once existed on the Red Planet.”

NASA’s article offers an explainer of what Lewis and his team did to differentiate their findings from possible false positives:

Lewis analyzed a range of organic salts mixed with an inert silica powder to replicate a Martian rock. He also investigated the impact of adding perchlorates to the silica mixtures. Perchlorates are salts containing chlorine and oxygen, and they are common on Mars. Scientists have long worried that they could interfere with experiments seeking signs of organic matter.

Indeed, researchers found that perchlorates did interfere with their experiments, and they pinpointed how. But they also found that the results they collected from perchlorate-containing samples better matched SAM data than when perchlorates were absent, bolstering the likelihood that organic salts are present on Mars.

This indirect evidence isn’t enough to state with certainty that these salts exist, but it’s definitely a clue that they may. Going forward, more intensive research into these salts and potentially hunting down the areas where they are concentrated could (and probably should) be prioritized.

Scientists find source of mysterious ‘fast radio bursts’ being sent to Earth

 

Scientists have found the source of a number of intense radio blasts that have been detected on Earth.

The signals, known as “fast radio bursts”, are intense but very short: they last less than a second but contain more energy that the Sun puts out in a whole year.

They were first discovered in 2007 but have remained largely mysterious since, even as researchers have catalogued up to 1,000 of them in the years since. The extremity of the blasts have led to speculation that they are the result of everything from extraterrestrial technology to unknown physical phenomena.

But, in the new study, researchers tracked down the source of eight of those bursts to their exact locations. Five of them were found within spiral galaxies, placed along the their outstretched curvy tentacles.

That discovery not only helps the search for the location of the blasts, but their cause too – the discovery helps narrow down the possible explanations.

“We don’t know what causes FRBs, so it’s really important to use context when we have it,” said Northwestern’s Wen-fai Fong, a co-author of the study. “Because spiral arms are signs of stars being born, this was a surprise, offering a major clue that FRBs must correlate with star formation.”

The new research, conducted using the Hubble Space Telescope and by astronomers from a range of institutions, is accepted.

“Our results are new and exciting. This is the first high-resolution view of a population of FRBs, and Hubble reveals that five of them are localized near or on a galaxy’s spiral arms,” said Alexandra Mannings of the University of California, Santa Cruz, the study’s lead author.

“Most of the galaxies are massive, relatively young, and still forming stars. The imaging allows us to get a better idea of the overall host-galaxy properties, such as its mass and star-formation rate, as well as probe what’s happening right at the FRB position because Hubble has such great resolution.”

The study seems to rule out suggestions that they the bursts come from the deaths of the youngest and most massive stars. It also seems to indicate they are not coming from the merging of neutron stars, which are the crushed cores of stars that die in supernovae, since the galaxies they were spotted in are too young and such stars tend not to be found on a spiral galaxy’s arms.

It does however suggest that the primary theory about fast radio bursts or FRBs – that they are the result of outbursts from young magnetars, or neutron stars with very powerful magnetic fields – is correct.

“Owing to their strong magnetic fields, magnetars are quite unpredictable,” Fong said.

“In this case, the FRBs are thought to come from flares from a young magnetar. Massive stars go through stellar evolution and becomes neutron stars, some of which can be strongly magnetized, leading to flares and magnetic processes on their surfaces, which can emit radio light. Our study fits in with that picture and rules out either very young or very old progenitors for FRBs.”

It also helps strengthen the connection between FRBs and massive, star-forming galaxies. Previous studies were not able to rule out that the blasts were coming from dwarf galaxies that were hidden by a more masssive one – but the new study allowed researchers to rule out such hidden dwarf galaxies.

Europe starts tests for automated asteroid spotters.

 

BERLIN (AP) — Scientists said they have switched on a new telescope at the European Southern Observatory as part of an effort to create an automated network for spotting asteroids that might pose a risk to Earth.

The 56-centimeter telescope that's now seen "first light" at the La Silla Observatory in Chile, known as TBT2, will work together with a twin in Cebreros, Spain, to test whether the same object in space can be detected with one device and then tracked by another.

The tests are a precursor to a planned network of automated telescopes being developed by ESO and the European Space Agency. The project, called Flyeye, will survey the night sky for fast-moving objects and flag those that could become a threat to human researchers for further investigation.

More than 900,000 asteroids have been catalogued in the Solar System and about 25,000 have an orbit that brings them close to Earth. The European Space Agency keeps a risk list of more than 1,000 such objects that are closely tracked.

A meteor that crashed near Chelyabinsk, Russia, in 2013, caused hundreds of injuries due to flying glass and splinters. While such events are rare, scientists say there are large numbers of such objects in space that haven't been detected and could cause significant damage if they struck populated areas.

The first Flyeye telescope is scheduled to be installed in Sicily next year.

Early black holes may be the seeds key to galaxies behemoths.

A new black hole breaks the record - not for being the smallest or the biggest - but for being right in the middle. The recently discovered ‘Goldilocks’ black hole is part of a missing link between two populations of black holes: small black holes made from stars and supermassive giants in the nucleus of most galaxies. In a joint effort, researchers from the University of Melbourne and Monash University have uncovered a black hole approximately 55,000 times the mass of the sun, a fabled “intermediate-mass” black hole.

Lead author and University of Melbourne PhD student, James Paynter, said the latest discovery sheds new light on how supermassive black holes form. “While we know that these supermassive black holes lurk in the cores of most, if not all galaxies, we don’t understand how these behemoths are able to grow so large within the age of the Universe,” he said. The new black hole was found through the detection of a gravitationally lensed gamma-ray burst. The gamma-ray burst, a half-second flash of high-energy light emitted by a pair of merging stars, was observed to have a tell-tale ‘echo’. This echo is caused by the intervening intermediate-mass black hole, which bends the path of the light on its way to Earth, so that astronomers see the same flash twice. Powerful software developed to detect black holes from gravitational waves was adapted to establish that the two flashes are images of the same object. “This newly discovered black hole could be an ancient relic - a primordial black hole - created in the early Universe before the first stars and galaxies formed,” said study co-author, Professor Eric Thrane from the Monash University School of Physics and Astronomy and Chief Investigator for the ARC Centre of Excellence for Gravitational Wave Discovery (OzGrav). “These early black holes may be the seeds of the supermassive black holes that live in the hearts of galaxies today.” Paper co-author, gravitational lensing pioneer, Professor Rachel Webster from the University of Melbourne said the findings have the potential to help scientists make even greater strides. “Using this new black hole candidate, we can estimate the total number of these objects in the Universe. We predicted that this might be possible 30 years ago, and it is exciting to have discovered a strong example.” The researchers estimate that some 46,000 intermediate mass black holes are in the vicinity of our Milky Way galaxy.

Lightning strikes will more than double in Arctic as climate warms.

 

In 2019, the National Weather Service in Alaska reported spotting the first-known lightning strikes within 300 miles of the North Pole. Lightning strikes are almost unheard of above the Arctic Circle, but scientists led by researchers at the University of California, Irvine have published new research in the journal Nature Climate Change detailing how Arctic lightning strikes stand to increase by about 100 percent over northern lands by the end of the century as the climate continues warming. 

"We projected how lightning in high-latitude boreal forests and Arctic tundra regions will change across North America and Eurasia," said Yang Chen, a research scientist in the UCI Department of Earth System Science who led the new work. "The size of the lightning response surprised us because expected changes at mid-latitudes are much smaller."
The finding offers a glimpse into the changes that're in store for the Arctic as the planet continues warming; it suggests Arctic weather reports during summertime will be closer to those seen today far to the south, where lightning storms are more common.
James Randerson, a professor in UCI's Department of Earth System Science who co-authored the study, was part of a NASA-led field campaign that studied wildfire occurrence in Alaska during 2015, which was a extreme year for wildfires in the state. "2015 was an exceptional fire year because of a record number of fire starts," Randerson said. "One thing that got us thinking was that lightning was responsible for the record-breaking number of fires."
This led Chen to look at over-twenty-year-old NASA satellite data on lighting strikes in northern regions, and construct a relationship between the flash rate and climatic factors. By using future climate projections from multiple models used by the United Nations, the team estimated a significant increase in lightning strikes as a result of increases in atmospheric convection and more intense thunderstorms.
A lightning strike bump could open a Pandora's box of related troubles. Fires, Randerson explained, burn away short grasses, mosses, and shrubs that are important components of Arctic tundra ecosystems. Such plants cover much of the landscape, and one thing they do is keep the seeds of trees from taking root in the soil. After a fire burns away low-lying plants, however, seeds from trees can more easily grow on bare soil, allowing forests stands to expand north. Evergreen forests will replace what's typically a snow-covered landscape; snow's white hue reflects sunlight back out into space, but darker forests absorb solar energy, helping warm the region even further.
And there's more trouble: more fires mean more permafrost—perennially frozen soil that defines much of the Arctic landscape—will melt as the fires strip away protective insulative layers of moss and dead organic matter that keep soils cool. Permafrost stores a lot of organic carbon that, if melted out of the ice, will convert to greenhouse gases carbon dioxide and methane, which, when released, will drive even more warming.
The lighting finding comes of the heels of another study that, led by Randerson, published in the Journal of Geophysical Research on Monday, April 5 describes how amplified Arctic warming and the melting of the Greenland ice sheet will scramble food webs in the surrounding oceans.
Now, Chen and Randerson say, scientists need to start paying more attention to the frequency of Arctic lightning strikes so they can gauge how the story unfolds in the coming decades.
"This phenomenon is very sporadic, and it's very difficult to measure accurately over long time periods," said Randerson. "It's so rare to have lightning above the Arctic Circle." Their results, he hopes, will galvanize calls for new satellite missions that can monitor Arctic and boreal latitudes for lightning strikes and the fires they might ignite.
Back in 2019, the National Weather Service in Alaska released a special announcement about the North Pole lightning strikes. Such announcements, however, may struggle to make headlines by the end of the century.

Nasa drops Mars helicopter Ingenuity onto surface.

 

Nasa’s Perseverance rover has dropped Ingenuity, the helicopter that will conduct the first controlled flight on another planet, onto the surface of Mars.
The helicopter fell four inches from the belly of Perseverance onto Mars.
It means that the helicopter is now looking after itself: heating and powering itself, which includes gathering solar energy from panels attached to its body. Temperatures through the night can drop as low as -54 degrees celsius, and an on-board heater aims to ensure that its battery and other components are protected from any damage.
At some point after 11 April, and when preparations are over, Ingenuity will take off for the first ever powered flight on any other planet. It could do so as many as five times over the following month, Nasa said – before
its test period is over and it will shut down to lie on the surface forever.

While the four inches from the bottom of the rover to the surface of Mars might seem small, they were among the most critical parts of the mission. They were the end of a process that began with Ingenuity turning around so that it was lying flat to drop onto the surface, and it was key that Ingenuity made it through safely to ensure it could take off.

Nasa also noted that those four inches came at the end of a 293 million mile journey that took the helicopter and its rover from Earth to Mars.

The space agency has not said exactly when the helicopter will take off, only that it will happen “no earlier than” 11 April. Before that happens, Nasa will hae to ensure that its battery is recharging properly, its motors and sensors are working as expected, and unlocking the rotor blades that will carry it.

The first flight will see the helicopter take off, hover a few feet above the ground for half a minute, and then land back down again.

That will be a major test of the technology that has been developed to ensure that Ingenuity can fly safely despite the very thin atmosphere on Mars. It will also represent the first time any object has conducted a power flight on another planet.

If that test is successful, the team will continue to fly further and higher over the 30-day mission period.

Nasa says that Ingenuity’s testing is intended primarily as a technology demonstration, and a proof of the work done to ensure it can fly. It will not conduct any research as it does so.

Perseverance will be at a safe distance throughout that testing, continuing its scientific work.

Scientists detect world's coldest cloud hovering over Pacific Ocean.

 

Storms near Nauru on Dec. 29, 20118 captured in infrared by an orbiting satellite. The cold parts of the clouds are in purple and the warm Pacific Ocean is in orange. (Image credit: National Centre for Earth Observation)
A severe thunderstorm cloud that formed over the Pacific Ocean in 2018 reached the coldest temperatures ever recorded, according to a new study.
The very top of the storm cloud reached a bone-chilling minus 167.8 degrees Fahrenheit (minus 111 degrees Celsius), colder than any storm cloud measured before. Thunderstorms and tropical cyclones, a circular low-pressure storm, can reach very high altitudes — up to 11 miles (18 kilometers) from the ground  — where the air is much cooler, according to a statement from the U.K.'s National Center for Earth Observation.
But this new temperature is on another level. The top of the storm cloud was about  86 F (30 C) colder than typical storm clouds, according to the statement. The beast of a storm loomed about 249 miles (400 km) south of Nauru in the Southwest Pacific on Dec. 29, 2018, and its clouds' temperature was picked up by an infrared sensor aboard the U.S.'s NOAA-20 satellite orbiting the planet.

Storms typically spread out into an anvil-like shape when they reach the top of the troposphere, the lowest layer of Earth's atmosphere. But if a storm has a lot of energy, it will shoot into the next layer, the stratosphere. This phenomenon, known as an "overshooting top," pushes storm clouds to very high altitudes, where it's bitterly cold.

Overshooting tops are "reasonably common," lead author Simon Proud, a research fellow at the National Centre for Earth Observation and at Oxford University. Typically, an overshooting top cools by about 12.6 F (7 C) for every kilometer it rises in the stratosphere, he said.

But this storm was particularly extreme. "This storm achieved an unprecedented temperature that pushes the limits of what current satellite sensors are capable of measuring," Proud said in the statement. "We found that these really cold temperatures seem to be becoming more common."

In the last three years, scientists have logged the same number of extremely cold temperatures in clouds as they did in the 13 years before that, he added. "This is important, as thunderstorms with colder clouds tend to be more extreme, and more hazardous to people on the ground due to hail, lightning and wind."

This particular storm may have been energized by a combination of very warm water in the region and eastward-moving wind, according to the BBC. However, it's not clear why these colder temperatures in storm clouds are becoming more common. 

"We now need to understand if this increase is due to our changing climate or whether it is due to a 'perfect storm' of weather conditions producing outbreaks of extreme thunderstorms in the last few years," Proud said.

Mysterious Interstellar Visitor May Be the Most Pristine Comet Ever Found.

New observations with the European Southern Observatory’s Very Large Telescope (ESO’s VLT) indicate that the rogue comet 2I/Borisov, which is only the second and most recently detected interstellar visitor to our Solar System, is one of the most pristine ever observed. Astronomers suspect that the comet most likely never passed close to a star, making it an undisturbed relic of the cloud of gas and dust it formed from.

2I/Borisov was discovered by amateur astronomer Gennady Borisov in August 2019 and was confirmed to have come from beyond the Solar System a few weeks later. “2I/Borisov could represent the first truly pristine comet ever observed,” says Stefano Bagnulo of the Armagh Observatory and Planetarium, Northern Ireland, UK, who led the new study published today in Nature Communications. The team believes that the comet had never passed close to any star before it flew by the Sun in 2019.

New observations with the European Southern Observatory’s Very Large Telescope (ESO’s VLT) indicate that the rogue comet 2I/Borisov, which is only the second and most recently detected interstellar visitor to our Solar System, is one of the most pristine ever observed. This video summarizes new findings on this mysterious alien visitor. Credit: ESO

Bagnulo and his colleagues used the FORS2 instrument on ESO’s VLT, located in northern Chile, to study 2I/Borisov in detail using a technique called polarimetry.^[1] Since this technique is regularly used to study comets and other small bodies of our Solar System, this allowed the team to compare the interstellar visitor with our local comets.

The team found that 2I/Borisov has polarimetric properties distinct from those of Solar System comets, with the exception of Hale–Bopp. Comet Hale–Bopp received much public interest in the late 1990s as a result of being easily visible to the naked eye, and also because it was one of the most pristine comets astronomers had ever seen. Prior to its most recent passage, Hale–Bopp is thought to have passed by our Sun only once and had therefore barely been affected by solar wind and radiation. This means it was pristine, having a composition very similar to that of the cloud of gas and dust it — and the rest of the Solar System — formed from some 4.5 billion years ago.

This image was taken with the FORS2 instrument on ESO’s Very Large Telescope in late 2019, when comet 2I/Borisov passed near the Sun. Since the comet was traveling at breakneck speed, around 175,000 kilometers per hour, the background stars appeared as streaks of light as the telescope followed the comet’s trajectory. The colors in these streaks give the image some disco flair and are the result of combining observations in different wavelength bands, highlighted by the various colors in this composite image. Credit: ESO/O. Hainaut

By analyzing the polarisation together with the color of the comet to gather clues on its composition, the team concluded that 2I/Borisov is in fact even more pristine than Hale–Bopp. This means it carries untarnished signatures of the cloud of gas and dust it formed from.

“The fact that the two comets are remarkably similar suggests that the environment in which 2I/Borisov originated is not so different in composition from the environment in the early Solar System,” says Alberto Cellino, a co-author of the study, from the Astrophysical Observatory of Torino, National Institute for Astrophysics (INAF), Italy.

Olivier Hainaut, an astronomer at ESO in Germany who studies comets and other near-Earth objects but was not involved in this new study, agrees. “The main result — that 2I/Borisov is not like any other comet except Hale–Bopp — is very strong,” he says, adding that “it is very plausible they formed in very similar conditions.”

“The arrival of 2I/Borisov from interstellar space represented the first opportunity to study the composition of a comet from another planetary system and check if the material that comes from this comet is somehow different from our native variety,” explains Ludmilla Kolokolova, of the University of Maryland in the US, who was involved in the Nature Communications research.
Bagnulo hopes astronomers will have another, even better, opportunity to study a rogue comet in detail before the end of the decade. “ESA is planning to launch Comet Interceptor in 2029, which will have the capability of reaching another visiting interstellar object, if one on a suitable trajectory is discovered,” he says, referring to an upcoming mission by the European Space Agency.

Even without a space mission, astronomers can use Earth’s many telescopes to gain insight into the different properties of rogue comets like 2I/Borisov. “Imagine how lucky we were that a comet from a system light-years away simply took a trip to our doorstep by chance,” says Bin Yang, an astronomer at ESO in Chile, who also took advantage of 2I/Borisov’s passage through our Solar System to study this mysterious comet. Her team’s results are published in Nature Astronomy.

Yang and her team used data from the Atacama Large Millimeter/submillimeter Array (ALMA), in which ESO is a partner, as well as from ESO’s VLT, to study 2I/Borisov’s dust grains to gather clues about the comet’s birth and conditions in its home system.

They discovered that 2I/Borisov’s coma — an envelope of dust surrounding the main body of the comet — contains compact pebbles, grains about one millimeter in size or larger. In addition, they found that the relative amounts of carbon monoxide and water in the comet changed drastically as it neared the Sun. The team, which also includes Olivier Hainaut, says this indicates that the comet is made up of materials that formed in different places in its planetary system.
The observations by Yang and her team suggest that matter in 2I/Borisov’s planetary home was mixed from near its star to further out, perhaps because of the existence of giant planets, whose strong gravity stirs material in the system. Astronomers believe that a similar process occurred early in the life of our Solar System.
While 2I/Borisov was the first rogue comet to pass by the Sun, it was not the first interstellar visitor. The first interstellar object to have been observed passing by our Solar System was ʻOumuamua, another object studied with ESO’s VLT back in 2017. Originally classified as a comet, ʻOumuamua was later reclassified as an asteroid as it lacked a coma.

1. Polarimetry is a technique to measure the polarisation of light. Light becomes polarized, for example, when it goes through certain filters, like the lenses of polarized sunglasses or cometary material. By studying the properties of sunlight polarized by a comet’s dust, researchers can gain insights into the physics and chemistry of comets..

Why One Side of Earth Is Rapidly Getting Colder Than the Other

 In a new study, scientists from the University of Oslo say one side of Earth’s interior is losing heat much faster than the other side—and the culprit is practically as old as time.

The research, published in Geophysical Research Letters, uses computer models of the last 400 million years to calculate how “insulated” each hemisphere was by continental mass, which is a key quality that holds heat inside instead of releasing it. The pattern goes all the way back to Pangaea.
Earth has a red hot liquid interior that warms the entire planet from inside. It spins, too, generating both gravity and Earth’s magnetic field. This holds our protective atmosphere close to Earth’s surface.
Over the extremely long term, this interior will continue to cool until Earth is more like Mars. The surprise in the new study is how unevenly the heat is dissipating, but the reason makes intuitive sense: Parts of Earth have been insulated by more landmass, creating something of a Thermos layer that traps heat.

This contrasts with how Earth loses most of its heat: “Earth’s thermal evolution is largely controlled by the rate of heat loss through the oceanic lithosphere,” the study authors write. Why is this the site of the greatest loss? For that, we need a quick-and-dirty run-through of continental drift. 

Earth’s mantle is like a convection oven that powers a treadmill. Every day, seafloor surface moves a tiny bit; new seafloor is born from the magma that erupts at the continental divide, while old seafloor is smashed and melted beneath existing continental landmass.

To study how Earth’s interior heat behaves, the scientists built a model that divides Earth into African and Pacific hemispheres, then divides Earth’s entire surface into a grid by half degrees latitude and longitude.

The scientists combined several previous models for things like seafloor age and continental positions during the last 400 million years. Then, the team crunched the numbers for how much heat each grid cell contains over its long life. This paved the way to calculate the rate of cooling overall, where the researchers found the Pacific side has cooled much faster.

 Accumulated mantle heat loss (oceanic + continental) over the past 400 Myrs. Regions above the Pacific and African large low shear velocity provinces are shown using blue and orange lines. Dashed, light-colored meridians indicate the separation of the Pacificand African hemispheres.

The seafloor is far thinner than the bulky landmass, and temperature from within Earth is “quenched” by the enormous volume of cold water that’s above it. Think of the gigantic Pacific Ocean compared with the opposite-side landmasses of Africa, Europe, and Asia—it makes sense that heat dissipates more quickly from the biggest seafloor in the world.

Previous research on this seafloor effect only went back 230 million years, meaning the new model, which goes back 400 million years, almost doubles the timeframe being studied.

There’s a surprising contradiction in the findings. The Pacific hemisphere has cooled about 50 Kelvin more than the African hemisphere, but the “consistently higher plate velocities of the Pacific hemisphere during the past 400 [million years]” suggest the Pacific was much hotter at a certain moment in time.

Was it covered by landmass at some point in the far distant past, keeping more heat inside? There are other possible explanations, but either way, the Pacific’s high tectonic activity today points to a heat disparity. The meltier the mantle, the more the plates can slide and slam together.

Student Astronomer Uses Ingenious Method to Find Galactic Missing Matter.

 

Distant galaxies used as ‘locator pins’ to detect ‘invisible’ gas cloud.

Half of the universe’s matter is ‘missing,’ but PhD student Yuanming Wang has developed an ingenious method to help track it down.

Astronomers have for the first time used distant galaxies as ‘scintillating pins’ to locate and identify a piece of the Milky Way’s missing matter.

For decades, scientists have been puzzled as to why they couldn’t account for all the matter in the universe as predicted by theory. While most of the universe’s mass is thought to be mysterious dark matter and dark energy, 5 percent is ‘normal matter’ that makes up stars, planets, asteroids, peanut butter, and butterflies. This is known as baryonic matter.

However, direct measurement has only accounted for about half the expected baryonic matter.

Yuanming Wang, a doctoral candidate in the School of Physics at the University of Sydney, has developed an ingenious method to help track down the missing matter. She has applied her technique to pinpoint a hitherto undetected stream of cold gas in the Milky Way about 10 light years from Earth. The cloud is about a trillion kilometers long and 10 billion kilometers wide but only weighing about the mass of our Moon.

The results, published in the Monthly Notices of the Royal Astronomical Society, offer a promising way for scientists to track down the Milky Way’s missing matter.

“We suspect that much of the ‘missing’ baryonic matter is in the form of cold gas clouds either in galaxies or between galaxies,” said Ms Wang, who is pursuing her PhD at the Sydney Institute for Astronomy.

“This gas is undetectable using conventional methods, as it emits no visible light of its own and is just too cold for detection via radio astronomy,” she said.

What the astronomers did is look for radio sources in the distant background to see how they ‘shimmered’.

“We found five twinkling radio sources on a giant line in the sky. Our analysis shows their light must have passed through the same cold clump of gas,” Ms Wang said.

Just as visible light is distorted as it passes through our atmosphere to give stars their twinkle, when radio waves pass through matter, it also affects their brightness. It was this ‘scintillation’ that Ms. Wang and her colleagues detected.

Dr. Artem Tuntsov, a co-author from Manly Astrophysics, said: “We aren’t quite sure what the strange cloud is, but one possibility is that it could be a hydrogen ‘snow cloud’ disrupted by a nearby star to form a long, thin clump of gas.”

Hydrogen freezes at about minus 260 degrees and theorists have proposed that some of the universe’s missing baryonic matter could be locked up in these hydrogen ‘snow clouds’. They are almost impossible to detect directly.

“However, we have now developed a method to identify such clumps of ‘invisible’ cold gas using background galaxies as pins,” Ms. Wang said.

Ms. Wang’s supervisor, Professor Tara Murphy, said: “This is a brilliant result for a young astronomer. We hope the methods trailblazed by Yuanming will allow us to detect more missing matter.”

The data to find the gas cloud was taken using the CSIRO’s Australian Square Kilometre Array Pathfinder (ASKAP) radio telescope in Western Australia.

Dr. Keith Bannister, Principal Research Engineer at CSIRO, said: “It is ASKAP’s wide field of view, seeing tens of thousands of galaxies in a single observation that allowed us to measure the shape of the gas cloud.”

Professor Murphy said: “This is the first time that multiple ‘scintillators’ have been detected behind the same cloud of cold gas. In the next few years, we should be able to use similar methods with ASKAP to detect a large number of such gas structures in our galaxy.”

Ms. Wang’s discovery adds to a growing suite of tools for astronomers in their hunt for the universe’s missing baryonic matter.  By the late Jean-Pierre Macquart from Curtin University who used CSIRO’s ASKAP telescope to estimate a portion of matter in the intergalactic medium using fast radio bursts as ‘cosmic weigh stations.’

Earth has been habitable for billions of years – what are the chances?

 

We know the Earth has the potential to change climate rapidly, so we definitely know it can change over geological timescales. What are the chances it has remained able to support life.

It took evolution 3 or 4 billion years to produce Homo sapiens. If the climate had completely failed just once in that time then evolution would have come to a crashing halt and we would not be here now. So to understand how we came to exist on planet Earth, we’ll need to know how Earth managed to stay fit for life for billions of years.

This is not a trivial problem. Current global warming shows us that the climate can change considerably over the course of even a few centuries. Over geological timescales, it is even easier to change climate. Calculations show that there is the potential for Earth’s climate to deteriorate to temperatures below freezing or above boiling in just a few million years.

We also know that the Sun has become 30 per cent more luminous since life first evolved. In theory, this should have caused the oceans to boil away by now, given that they were not generally frozen on the early Earth – this is known as the “faint young Sun paradox”. Yet, somehow, this habitability puzzle was solved.

Scientists have come up with two main theories. The first is that the Earth could possess something like a thermostat – a feedback mechanism (or mechanisms) that prevents the climate ever wandering to fatal temperatures.

The second is that, out of a large number of planets, perhaps some just make it through by luck, and Earth is one of those. This second scenario is made more plausible by the discoveries in recent decades of many planets outside our solar system – so-called exoplanets. Astronomical observations of distant stars tell us that many have planets orbiting them, and that some are of a size and density and orbital distance such that temperatures suitable for life are theoretically possible. It has been estimated that there are at least 2 billion such candidate planets in our galaxy alone.

Scientists would love to travel to these exoplanets to investigate whether any of them have matched Earth’s billion years of climate stability. But even the nearest exoplanets, those orbiting the star Proxima Centauri, are more than four light-years away. Observational or experimental evidence is hard to come by.

Instead, I explored the same question through modelling. Using a computer program designed to simulate climate evolution on planets in general (not just Earth), I first generated 100,000 planets, each with a randomly different set of climate feedbacks. Climate feedbacks are processes that can amplify or diminish climate change – think for instance of sea ice melting in the Arctic, which replaces sunlight-reflecting ice with sunlight-absorbing open sea, which in turn causes more warming and more melting.

In order to investigate how likely each of these diverse planets was to stay habitable over enormous (geological) timescales, I simulated each 100 times. Each time the planet started from a different initial temperature and was exposed to a randomly different set of climate events. These events represent climate-altering factors such as supervolcano eruptions (like Mount Pinatubo but much much larger) and asteroid impacts (like the one that killed the dinosaurs). On each of the 100 runs, the planet’s temperature was tracked until it became too hot or too cold or else had survived for 3 billion years, at which point it was deemed to have been a possible crucible for intelligent life.

The simulation results give a definite answer to this habitability problem, at least in terms of the importance of feedbacks and luck. It was very rare (in fact, just one time out of 100,000) for a planet to have such strong stabilising feedbacks that it stayed habitable all 100 times, irrespective of the random climate events. In fact, most planets that stayed habitable at least once, did so fewer than 10 times out of 100. On nearly every occasion in the simulation when a planet remained habitable for 3 billion years, it was partly down to luck. At the same time, luck by itself was shown to be insufficient. Planets that were specially designed to have no feedbacks at all, never stayed habitable; random walks, buffeted around by climate events, never lasted the course.

This overall result, that outcomes depend partly on feedbacks and partly on luck, is robust. All sorts of changes to the modelling did not affect it. By implication, Earth must therefore possess some climate-stabilising feedbacks, but at the same time good fortune must also have been involved in it staying habitable. If, for instance, an asteroid or solar flare had been slightly larger than it was, or had occurred at a slightly different (more critical) time, we would probably not be here on Earth today. It gives a different perspective on why we are able to look back on Earth’s remarkable, enormously extended, history of life evolving and diversifying and becoming ever more complex to the point that it gave rise to us.

Scientists spot 6 alien worlds orbiting a star in strange harmony.

 

The planets around a star called TOI-178 know how to keep a beat  so smoothly, in fact, that scientists were able to discover new alien worlds by deciphering the system's music.

Astronomers poring through data from NASA's Transiting Exoplanet Survey Satellite (TESS) discovered three planets around a star dubbed TOI-178 (TOI stands for TESS Object of Interest). And when scientists looked at these observations more closely, they realized that the worlds seemed to be keeping time against each other. So they recruited some more instruments — and discovered the system hosts at least six planets, five of which tick off orbits in rhythm with the others. And unlike those of other synchronized systems, the planets are an unusually mixed bag.

"It is the first time we observe something like this," Kate Isaak, project scientist for the European Space Agency's Characterizing Exoplanet Satellite (CHEOPS), one of those additional instruments, said in a statement released by the University of Bern in Switzerland. "In the few systems we know with such a harmony, the density of planets steadily decreases as we move away from the star. In the TOI-178 system, a dense, terrestrial planet like Earth appears to be right next to a very fluffy planet with half the density of Neptune, followed by one very similar to Neptune."

Inspired by the mysterious TESS data showing three planets in an odd rhythm, the scientists behind the new research recruited additional instruments culminating in a dozen days of observing time with the CHEOPS telescope.

From those observations, the TOI-178 system appeared to include five planets, which orbited the star every 2, 3, 6, 10 and 20 days. But to the scientists, there appeared to be a gap in that sequence: They thought there should be another planet in the system, this one orbiting every 15 days.

Back to CHEOPS the researchers went, although they nearly missed their chance at studying the system in detail. Just as CHEOPS was due to take crucial observations of TOI-178, the satellite had to hustle away from a potential collision with a piece of space junk.

Despite the close call, all went smoothly in the end.

"To our great relief, this maneuver was done very efficiently and the satellite could resume observations just in time to capture the mysterious planet passing by," Nathan Hara, an astrophysicist at the University of Geneva and co-author on the new research, said in the statement. "A few days later, the data clearly indicated the presence of the additional planet and thus confirmed that there were indeed six planets in the TOI-178 system."

The innermost of those, it turns out, marches to a different beat, but the outer five orbit in harmony with each other. For every complete orbit of the outermost world, the next in completes three-quarters of an orbit, the middle world in the sequence makes two loops, then a planet that makes three orbits, and then a planet that makes six orbits; along the way, the planets occasionally line up, which caused the strange rhythm in the original TESS data.

Not only could the researchers spot the additional planets and sort out the complicated chain of orbits, but the scientists could also study the planets themselves, finding that these worlds range from 1.1 to 3 times the size of Earth, but with a range of densities, making them a curious mix of rocky super-Earths and gassy mini-Neptunes.

The scientists suspect that there may be more planets following the same chain of orbital alignments, although spotting these worlds would require longer periods of observation. Fortunately, because the star itself is so bright, the system is relatively easy to study; in particular, the researchers look forward to the data that NASA's James Webb Space Telescope and the European Extremely Large Telescope might be able to gather about the system once each begin work.

Neptune’s bumpy could reveal our solar system’s missing planets.

 

The modern solar system spins serenely, the planets locked in seemingly eternal circles around the sun. But it wasn’t always so. This tranquility appears to have emerged only after a gladiatorial period of planetary clashes—one in which titans ricocheted off each other, perhaps ejecting at least one rival sibling from the cosmic arena altogether.

Researchers have spent years scouring the solar system for clues of how that comparatively chaotic epoch might have played out. In a modest cluster of far-off rocks, David Nesvorny, a planetary scientist at the Southwest Research Institute, has found a figurative blood spatter suggestive of one particular conflict: a tussle between Neptune and an unknown planet that saw Neptune emerge victorious. His analysis, which appeared in late December in a not-yet-peer reviewed publication, adds further support to the notion that the solar system was once home to more than its current cadre of worlds.

To get this cohort of distant objects to pop out when you run the simulations, says Nathan Kaib, a planetary scientist at the University of Oklahoma who was not involved in the research, it seems like “you really need a planet to scatter [Neptune] off of.” That means, in theory, at least one extra planet may have been whizzing around the sun in eons past, knocking Neptune for a loop.

One way researchers can learn about events that took place more than four and a half billion years ago is by studying a current collection of ice balls known as the Kuiper Belt. Starting near Neptune’s orbit and extending outward from there, these frozen objects have been doing their own thing for eons, blind to most planetary drama.

The exception is the nearby Neptune, whose orbit has synched up with the orbits of many Kuiper Belt Objects (KBOs), including Pluto. This synchronization arises through subtle gravitational nudges from Neptune, which would have stopped those KBOs from forming in the first place. But since Pluto and its companions exist, researchers realized in the 80s and 90s, Neptune must have started out perhaps 10 to 20 percent closer to the sun and then slid outward later on (after Pluto and friends had already formed in peace).

But how did it relocate? One early idea was that it spiraled out smoothly as a result of regularly bumping into small objects, but a number of observations hinted at a more dramatic rearrangement: sometime in the solar system’s first millions of years, a number of near hits may have slingshotted planets into new positions on elliptical paths. Planetary scientists refer to this calamitous period euphemistically as an “instability.”

To get a better idea of what happened to Neptune during the instability, Nesvorny focused on one particular group of dozens of KBOs discovered over the last decade or so. Their orbits pass through the outskirts of the Kuiper Belt, but what really makes them special is how their paths tip roughly ten degrees out of the solar system’s flat disk—an indication that something pushed them out. “If you have certain orbit, it’s hard to tilt it differently,” Nesvorny says.

That something, according to new simulations from Nesvorny, is most likely a Neptune that slipped outward on an orbit with a just-so shape—one that falls somewhere between a perfect circle and a more severely squashed ellipse. Other scenarios just didn’t arrange this group of KBOs in the right place with the right slant.

To get Neptune moving in precisely that way would have taken a serious jolt, likely a close encounter with another planet of perhaps comparable mass. Previous studies, including work by Nesvorny, have suggested that the early solar system originally accommodated more giant planets than just Jupiter, Saturn, Uranus, and Neptune, a scenario that grows more likely if all the orbits went screwy for a while. “If you have an instability, you’re significantly more likely to lose planets than retain your original four,” Kaib says.

When Nesvorny runs hypothetical versions of the solar system in a simulation with a third ice giant (in addition to Uranus and Neptune), everything fits. If the mystery giant nearly collides with Neptune and Neptune’s orbit stretches as it moves out, giving the band of KBOs their distinctive 10 percent incline. The evidence is circumstantial, but suggestive.

“This is science,” he says. “You never know things for sure, but it’s compelling enough for me.”

Since Neptune survived the encounter, the additional ice giant was likely ejected from the solar system to wander the darkness of the Milky Way. However, if it didn’t receive quite enough of a kick to fly completely free of the sun’s gravity, it just might have come to rest perhaps 30 times farther from the sun than Neptune is today—exactly where some astronomers have predicted an unseen Planet Nine. The booted planet hangs around only around five percent of the time in simulations, Kaib says, but those are hardly unbeatable odds.

Better understanding the possible clashes between young planets, according to Nesvorny, is simply a matter of mapping the undisturbed outer reaches of the solar system in greater detail. This task will be a major goal for the upcoming Vera C. Rubin Observatory, which is expected to begin scientific operations in 2023.

“Because we have the Kuiper Belt,” he says, “it shouldn’t be that difficult to figure out what happened.