What color is the universe?

 

It is a bit tamer than you might imagine.

When you look up at the night sky, it's easy to think that the universe is a never-ending sea of blackness. But if you measured the visible light from all of the luminous celestial bodies out there, what would the average color of the universe be?
Let's get this out of the way first: It's not black.
"Black is not a color," Ivan Baldry, a professor at the Liverpool John Moores University Astrophysics Research Institute in the U.K., told Live Science. "Black is just the absence of detectable light." Instead, color is the result of visible light, which is created throughout the universe by stars and galaxies, he said. 

In 2002, Baldry and Karl Glazebrook, a distinguished professor at the Centre for Astrophysics and Supercomputing at the Swinburne University of Technology in Australia, co-led a study published in The Astrophysical Journal that measured the light coming from tens of thousands of galaxies and combined it into a singular spectrum that represented the entire universe.
In doing so, the pair and their colleagues were able to work out the average color of the universe.
The cosmic spectrum
Stars and galaxies emit waves of electromagnetic radiation, which is separated into different groups based on the length of the waves emitted. From shortest to longest wavelength, the groups include gamma-rays, X-rays, ultraviolet light, visible light, infrared radiation, microwaves and radio waves.
Visible light makes up a tiny portion of the electromagnetic spectrum in terms of the range of wavelengths, but it is the only part the naked eye can see. What we perceive as colors are actually just different wavelengths of visible light; reds and oranges have longer wavelengths, and blues and purples have shorter wavelengths. 

The visible spectrum of a star or a galaxy is a measure of the brightness and wavelengths of light that the star or galaxy emits, which, in turn, can be used to determine the average color of the star or galaxy, Baldry said.

In 2002, Australia's 2dF Galaxy Redshift Survey — which was the largest survey of galaxies ever carried out at the time — captured the visible spectra of more than 200,000 galaxies from across the observable universe. By combining the spectra of all these galaxies, Baldry and Glazebrook's team was able to create a visible light spectrum that accurately represented the entire universe, known as the cosmic spectrum.

The comic spectrum "represents the sum of all the energy in the universe emitted at different optical wavelengths of light," Baldry and Glazebrook wrote in a separate non-peer-reviewed in 2002 based on their discovery. The cosmic spectrum, in turn, allowed them to determine the average color of the universe.  

Color conversion 

The researchers used a color-matching computer program to convert the cosmic spectrum into a single color visible to humans, Baldry said.

Our eyes have three types of light-sensitive cones, each of which helps us perceive a different range of visible light wavelengths. This means that we have certain blind spots where we cannot properly register certain colors of wavelengths between these ranges, Baldry and Glazebrook wrote in their online paper. The colors we see also depend on what our reference for white light is as we are observing an object. For instance, the color of an object may appear different in a brightly lit room compared with the outdoors on an overcast day.

However, the CIE color spaces, created by the International Commission on Illumination in 1931, compensate for our visual limitations by attributing a color to different wavelength combinations as seen by a standardized human observer, which is what the team's computer models used.
The team determined that the average color of the universe is a beige shade not too far off from white. Although this is a rather boring finding, it is not a surprising one, considering that white light is the result of combining all the different wavelengths of visible light and the cosmic spectrum includes such a wide range of wavelengths.
The new color was eventually named "cosmic latte," based on the Italian word for milk, after a poll of the whole research team. Other suggestions included cappuccino cosmico, Big Bang beige and primordial clam chowder.

Unshifting the red
A key concept of the cosmic spectrum is that it represents the light of the universe "as originally envisaged," Balrdy and Glazebrook wrote in their online paper. This means that it represents the light as it was emitted throughout the universe, not just as it appears to us on Earth today.
Like all waves, light gets stretched over vast distances because of the Doppler effect. As light gets stretched, its wavelength increases and its color moves toward the red end of the spectrum, known by astronomers as redshift. This means that the light we see is not the same color it was when it was first emitted. 

"We removed the effect of redshift from the spectra of the galaxies," Baldry said. "So, it is the spectra of the galaxies when they emitted the light."

Cosmic latte is, therefore, the color you would see if you could look down on the universe from above and see all the light coming from every galaxy, star and gas clouds all at once, Baldry said.

NASA is training robots like humans to explore caves on Mars

 

When searching for signs of life on other planets, scientists say caves are a crucial place to look. But how can a team on Earth effectively explore intricate, dark, unfamiliar landscapes on another world?
NASA and Boston Dynamics have found an answer: Fully autonomous robots.
Caves are one of the most likely places to find signs of both current and past life on other planets because they are capable of protecting life from cosmic rays and extreme temperature fluctuations around our solar system. A NASA project called BRAILLE is now working on exploring Mars-like caves that already exist on Earth in order to hone key technologies for future missions. 

According to researchers, the project has enabled the first-ever fully autonomous robotic exploration of these types of caves, which are several hundred meters long and limit communication with the surface. As the robots explore, with no prior information about the environment, a team of researchers outside the cave simultaneously performs actions that scientists on Earth would be executing during a real Martian mission. 

The research, which project lead Ali Agha said could "fundamentally change how we think about future missions," is now in year three of four in its quest to journey to the moon, the red planet and beyond.
But researchers are interested in exploring caves for another reason beyond finding signs of life: caves provide obvious natural shelters for future astronauts exploring Mars or the moon.

"Future potential human exploration missions can benefit from robots in many different ways," Agha told CBS News. "Particularly, robots can be sent in precursor missions to provide more information about the destination before humans land on those destinations. In addition, robots can accompany astronauts during the missions to help with scouting certain terrains or with logistics and many tasks that can make astronauts' missions safer and more efficient."

So, how is designing a Mars robot different from designing an Earth robot? They are similar in a lot of ways, Agha said, especially when it comes to the AI robot brain, called NeBula, and its ability to process information and make decisions when they don't have contact with scientists on Earth. 

But when it comes to the robot body, that's where things get more complicated. Scientists need to consider temperature management, shielding the robots from radiation, as well as the severe power and energy constraints that come with trekking to a far-away world — all aspects not previously considered on Earth. 

Boston Dynamics' Spot robot has proven an extremely viable body for NeBula.

"SPOT is one of the most capable robots that we have and it is amazing to see how it successfully reacts to high-level decisions and commands coming from the robot brain and how it can maintain stability over rough and extreme terrains," Agha said. "In addition to our capable traditional wheeled rovers, the ability to "walk" is a huge asset when dealing with uneven terrains with no roads and no flat surfaces."

There are three main factors for the robot's success:

• It needs to be able to carry enough payload for its eyes, ears and brain to be able to traverse the challenging Martian or lunar terrain.
• It needs to carry a meaningful amount of science instruments.
• It must prove it can maintain a "reasonable" level of stability, speed and endurance on another world. 

"We have these multiple mobile robots that can carry different instruments, as opposed to one big robot that's going to have trouble traversing its terrain," said deputy project lead Benjamin Morrell, referring to past Martian rovers. 

"Boston Dynamics Spot robot is one of the few robots that satisfy these constraints simultaneously," Agha said. "So integrating our robot brain, NeBula, on Spot has been pushing the boundaries of what was possible in exploring unknown Mars-like environments."

The robots typically cannot communicate from inside the cave, so scientists eagerly await their return to the surface for data, which could include a 3D map of the cave's interior, information on science targets or general findings about the environment. 

Some of the robots are also equipped with arms to bring back small samples from the cave walls for analysis. Researchers hope that these robots will be able to autonomously carry out parts of future missions in space, after humans have built up a certain level of trust with them. 

"The next-generation robot bodies and mechanical locomotion capabilities would enable new types of missions over terrains that were otherwise inaccessible by traditional rovers," Agha said. "Also, due to the increased speed and traversal capabilities, future missions can target destinations that are traditionally considered to be too far from landable regions on Mars.

No hope for life in Venus clouds

The amount of water in the atmosphere of Venus is so low that even the most drought-tolerant of Earth's microbes wouldn't be able to survive there, a new study has found. The findings seem to wipe out the hope stirred by last year's discovery of molecules potentially created by living organisms in the scorched planet's atmosphere that were seen as an indication of the possible presence of life. 

The new study looked at measurements from probes that flew through the atmosphere of Venus and acquired data about temperature, humidity and pressure in the thick sulfuric acid clouds surrounding the planet. From these values, the scientists were able to calculate the so-called water activity, the water vapor pressure inside the individual molecules in the clouds, which is one of the limiting factors for the existence of life on Earth.

"When we looked at the effective concentration of water molecules in those clouds, we found that it was a hundred times too low for even the most resilient Earth organisms to survive." John Hallsworth, a microbiologist at Queen's University in Belfast, U.K., and lead author of the paper, said in a news conference on Thursday (June 24). "That's an unbridgeable distance."

The findings are likely a disappointment for the Venus research community, which was invigorated last September by the discovery of phosphine, a compound made of atoms of phosphorus and hydrogen that on Earth can be associated with living organisms, in Venus' atmosphere. At that time, researchers suggested the phosphines may be produced by microorganisms residing in those clouds. 

On Earth, Hallsworth said, microorganisms can survive and proliferate in droplets of water in the atmosphere when temperatures allow. However, the findings of the new study, based on data from several Venus probes, leave zero chance of anything living in the clouds of Venus, he said.

"Living systems including microorganisms are composed mainly of water and without being hydrated, they can't be active and are unable to proliferate," Hallsworth said. 

Studies on microorganisms living in extreme conditions on Earth found that life can exist at temperatures as cold as minus 40 degrees Fahrenheit (minus 40 degrees Celsius). For water activity, which is measured on the scale from 0 to 1, the lowest survivable value is 0.585. The water activity level found in the molecules in the Venusian clouds was merely 0.004. 

NASA Ames astrobiologist Chris McKay, one of the co-authors of the paper, said in the news conference that the findings of the study were conclusive and the new fleet of space missions currently being prepared for Venus will not change anything about the hope for life on Earth's closest neighbor. 

"Our conclusion is based directly on measurements," McKay said in the briefing. "It's not a model, it's not an assumption. The missions that NASA just selected to go to Venus will do the same measurements again —  temperature, pressure — and they are going to come to very much the same conclusions because Venus is not changing on that type of time scale."

However, the researchers looked at data from other planets too and found that the clouds of Jupiter do provide sufficient water activity to theoretically support life. Data collected by the Galileo probe at altitudes between 26 and 42 miles (42 and 68 kilometers) above the surface of the gas giant suggest the water activity value to sit at 0.585, just above the survivable threshold. Temperatures in this region are also just about survivable, at around minus 40 degrees F. 

"Jupiter looks much more optimistic," McKay said. "There is at least a layer in the clouds of Jupiter where the water requirements are met. It doesn't mean that there is life, it just means that with respect to water, it would be OK."

High levels of ultraviolet radiation or lack of nutrients could, however, prevent that potential life from thriving, the researchers said, and completely new measurements would be needed to find whether it actually could be there or not. 

Hallsworth added that the technique used to calculate the water activity could also help determine the habitability of exoplanets.

"What excites me the most is that we can go down to the scale of water molecules for these distant planets and pinpoint their potential habitability," Hallsworth said.

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.’