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Largest comet ever discovered is heading towards the Sun. Nothing to worry about, though

This illustration shows the distant Comet Bernardinelli-Bernstein as it might look in the outer Solar System. Credit: NOIRLab/NSF/AURA/J. da Silva.

In June 2021, astronomers were stoked to announce the discovery of the Bernardinelli-Bernstein comet (C/2014 UN271), by far the largest comet ever measured. With a diameter of nearly 100 km (62 miles), Bernardinelli-Bernstein is about 1,000 larger than a typical comet in our solar system.

Scientists initially found the gargantuan comet zipping through the Oort cloud — a shell of predominantly icy debris in the outermost reaches of the solar system. They could even discern a glowing tail and coma, a sign that the comet may be approaching the warmer inner solar system. A new study due to be published in the Astrophysical Journal Letters has confirmed just that: the Bernardinelli-Bernstein comet will reach its perihelion, the point at which it is closest to the sun, sometime in 2031.

There’s no need to panic, though. Even at its closest position to the sun, the comet will still be very far away. Astronomers expect the comet to come within 11 astronomical units (AU) of the sun, where 1 AU is the distance between the Sun and Earth. That would place Bernardinelli-Bernstein safely away, just beyond Saturn’s orbit.

So, a decade from now, scientists will have the unique opportunity to study and image a comet in a weight class of its own from a safe distance. By then, the Vera C. Rubin Observatory, currently under construction on the El Penón peak of Cerro Pachón in northern Chile, should finally come online. The ground-based telescope will be equipped with state-of-the-art instruments, allowing it to study the nature of dark matter and perform sky surveys, as well as track comets.

The 2031 flyby will be a once in a 3.5 million year opportunity — the last time the comet came this close to the sun. The last time the Bernardinelli-Bernstein comet showed its glowy tail in the solar system, our genus (Homo) didn’t even exist. Its current inward journey began at a distance of over 40,000 AU, which is about one 7th of the distance to the nearest star. For comparison, Pluto is 39 AU from the Sun, on average. 

This image from the Dark Energy Survey (DES) is composed of some of the discovery exposures showing Comet Bernardinelli-Bernstein collected by the 570-megapixel Dark Energy Camera (DECam) mounted on the Víctor M. Blanco 4-meter Telescope at Cerro Tololo Inter-American Observatory (CTIO) in Chile. Credit: Dark Energy Survey/DOE/FNAL/DECam/CTIO/NOIRLab/NSF/AURA/P. Bernardinelli & G. Bernstein (UPenn).

The comet was discovered by Pedro Bernardinelli and Gary Bernstein, both astronomers at the University of Pennsylvania, while the two were combing through data collected by the 570-megapixel Dark Energy Camera (DECam) mounted on the Víctor M. Blanco 4-meter Telescope at Cerro Tololo Inter-American Observatory (CTIO) in Chile.

“We have the privilege of having discovered perhaps the largest comet ever seen — or at least larger than any well-studied one — and caught it early enough for people to watch it evolve as it approaches and warms up,” said Gary Bernstein in a statement. “It has not visited the Solar System in more than 3 million years.”

While Bernardinelli-Bernstein makes its long journey towards the inner solar system, astronomers won’t exactly stay idle. They will use every tool at their disposal to study the composition and origin of this massive relic. In the process, they may learn a thing or two about the composition of the early solar system and its formation as Oort cloud objects are believed to have remained relatively unchanged since the sun first formed billions of years ago.

“This is a much needed anchor on the unknown population of large objects in the Oort Cloud and their connection with early migration of the ice/gas giants soon after the Solar System was formed,” said Tod Lauer, an astronomer affiliated with the National Science Foundation’s NOIRLab.

“These observations demonstrate the value of long-duration survey observations on national facilities like the Blanco telescope,” says Chris Davis, National Science Foundation Program Director for NOIRLab. “Finding huge objects like Comet Bernardinelli-Bernstein is crucial to our understanding of the early history of our Solar System.”

Crumbled comet helps researchers understand how their tails form

Last year, researchers spotted what was going to be the brightest comet seen since 1997: C/2019 Y4 ATLAS. It is now helping us understand how comets form their tails.

The comet’s break up in April 2020, captured by Hubble. Image credits NASA / ESA / STScI / D. Jewitt (UCLA).

Much to their dismay, however, this body broke down into fragments sometime in April 2020, robbing everybody of a shining view. Not all is lost, however, as NASA and the European Space Agency’s Solar Orbiter managed to do a flyby of the fragments, giving us a very rare look at what happens after a comet breaks up.

The tail end

ATLAS was supposed to become easily visible even with the naked eye as it passed Earth in May of last year. But one month before that could happen, our satellites showed, ATLAS got progressively brighter. Finally, it crumbled before reaching Earth. The Hubble Space Telescope captured this event, despite it happening over 90 million miles away from our planet. Each fragment is around the size of an average house.

Still, the comet’s tail persisted after the breakdown, so the Solar Orbiter was tasked to observe the remains. All of the craft’s instruments were used to probe ATLAS’s remains for information, including an energetic particle detector, magnetometer, a radio wave detector, and solar wind analyzer.

Data from the magnetometer was particularly interesting, as it allowed ground control to see how the magnetic field of the comet’s tail interacted with the magnetic field carried through the solar system by the solar wind. This interaction is known to produce ion tails around comets, a fainter and smaller counterpart to their visible dust tails.

Based on the data recorded here, the team was able to model the magnetic field generated by the initial comet, revealing a surprising fact: it is weakest around the central dust tail. This is most likely produced by the comet’s ‘wake’ as it barrels through incoming solar winds. The comet’s ion tail is produced by this magnetic field warping in combination with chemical ions produced by the melting of the comet’s core.

“This is quite a unique event, and an exciting opportunity for us to study the makeup and structure of comet tails in unprecedented detail,” said Lorenzo Matteini, a solar physicist at Imperial College London and leader of the recent work, in a Royal Astronomical Society press release. “Hopefully with the Parker Solar Probe and Solar Orbiter now orbiting the Sun closer than ever before, these events may become much more common in future!”

The event, although it might seem inconsequential in the grand scheme of things, lets us understand comets and outer space just a little bit better. While we don’t have a practical use for such data right now, they might come in handy when and if humanity takes to the stars in meaningful numbers.

The findings have been presented at the National Astronomy Meeting 2021.

This image shows an artist’s impression of what the surface of the 2I/Borisov comet might look like.  2I/Borisov was a visitor from another planetary system that passed by our Sun in 2019, allowing astronomers a unique view of an interstellar comet. While telescopes on Earth and in space captured images of this comet, we don’t have any close-up observations of 2I/Borisov. It is therefore up to artists to create their own ideas of what the comet’s surface might look like, based on the scientific information we have about it. (SO/M. Kormesser)

Interstellar visitor 2I/Borisov is the most pristine comet ever observed

As an interstellar visitor–an object from outside the solar system–the rogue comet 2I/Borisov is already a source of great interest for astronomers. But researchers have now also discovered that this interstellar comet is composed of pristine material similar to that which exists when star systems first form.

Not only does this make 2I/Borisov even more exciting than previously believed, it means that studying the material that composes it and its coma –an envelope of gas and dust that surround comets– could unlock secrets of planetary system formation.

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 travelling at breakneck speed, around 175 000 kilometres per hour, the background stars appeared as streaks of light as the telescope followed the comet’s trajectory. The colours in these streaks give the image some disco flair and are the result of combining observations in different wavelength bands, highlighted by the various colours in this composite image. (ESO/O. Hainaut)
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 travelling at breakneck speed, around 175 000 kilometres per hour, the background stars appeared as streaks of light as the telescope followed the comet’s trajectory. The colours in these streaks give the image some disco flair and are the result of combining observations in different wavelength bands, highlighted by the various colours in this composite image. (ESO/O. Hainaut)

“2I/Borisov could represent the first truly pristine comet ever observed,” says Stefano Bagnulo of the Armagh Observatory and Planetarium, Northern Ireland, UK. The astronomer tells ZME Science: “We presume this is because it has travelled in the interstellar medium without interacting with any other stars before reaching the Sun.”

Bagnulo is the lead author of one of two papers published in the Nature family of journals detailing new in-depth analysis of 2I/Borisov.

Reflecting on 2I/Borisov

The team was able to make its detailed study of 2I/Borisov–the second interstellar comet found trespassing in our solar system after the cigar-shaped Oumuamua–using the Very Large Telescope (VLT) located in the Acatma Desert, Northern Chile.

In particular, they employed the FOcal Reducer and low dispersion Spectrograph (FORS2) instrument–a device capable of taking mages of relatively large areas of the sky with very high sensitivity–and a technique called polarimetry to unlock the comet’s secrets.

“Sunlight scattered by material, for instance, reflected by a surface, is partially polarised,” explains Bagnulo comparing this to polaroid sunglasses which absorb the polarised component of the light and thus dampen reflected light suppressing glare. “In astronomy, we are interested in that polarised radiation because it carries information about the structure and composition of the reflecting surface or scattering material.”

Bagnulo continues by explaining that because light reflected by a darker object is polarised more than the light reflected by a brighter object, polarimetry may be used to estimate the albedo of an asteroid. This makes it a tool regularly used to study comets and allowed the team to compare 2I/Borisov to comets that begin life in our solar system.

“We found that the polarimetric behaviour of 2I/Borisov is different than that of all other comets of our solar system, except for one, Comet Hale-Bopp,” Bagnulo says. “We suggest that this is because Hale-Bopp is a pristine comet.”

It also implies that 2I/Borisov and Halle-Bopp formed in similar environments, thus giving us a good picture of conditions in other planetary systems.

Whilst, Bagnulo and his team were conducting this research with data collected by the VLT, another team was using a different method to examine the material that comprises this interstellar comet.

The Secrets in the Dust of 2I/Borisov

Bin Yang, is an astronomer at ESO in Chile, who also took advantage of 2I/Borisov’s intrusion into the solar system to study this mysterious comet, but using the Atacama Large Millimeter/submillimeter Array (ALMA).

This image shows an artist’s impression of what the surface of the 2I/Borisov comet might look like.     2I/Borisov was a visitor from another planetary system that passed by our Sun in 2019, allowing astronomers a unique view of an interstellar comet. While telescopes on Earth and in space captured images of this comet, we don’t have any close-up observations of 2I/Borisov. It is therefore up to artists to create their own ideas of what the comet’s surface might look like, based on the scientific information we have about it. (SO/M. Kormesser)
This image shows an artist’s impression of what the surface of the 2I/Borisov comet might look like.  2I/Borisov was a visitor from another planetary system that passed by our Sun in 2019, allowing astronomers a unique view of an interstellar comet. While telescopes on Earth and in space captured images of this comet, we don’t have any close-up observations of 2I/Borisov. It is therefore up to artists to create their own ideas of what the comet’s surface might look like, based on the scientific information we have about it. (SO/M. Kormesser)

“I had the idea of observing the thermal emission from the dust particles in the coma of 2I/Borisov using ALMA. My co-author Aigen Li constructed theoretical models to fit the ALMA observation and set constraints on the dust properties,” Yang, the lead author of the second paper detailing the 2I/Borisov investigation, tells ZME Science. “The composition of 2I/Borisov is similar to solar system comets, consists of dust and various ices. The major ices are water ice, carbon monoxide ice and the minor species include hydrogen cyanide and ammonia.”

Yang goes on to explain that the team was not able to precisely determine the composition of 2I/Borisov’s dust component. The astronomer adds that it could be composed of silicates or carbonaceous materials or a mixture of both.

This image shows an artist’s close-up view of what the surface of the comet might look like.  2I/Borisov was a visitor from another planetary system that passed by our Sun in 2019, allowing astronomers a unique view of an interstellar comet. While telescopes on Earth and in space captured images of this comet, we don’t have any close-up observations of 2I/Borisov. It is therefore up to artists to create their own ideas of what the comet’s surface might look like, based on the scientific information we have about it. (ESO/M. Kormesser)
This image shows an artist’s close-up view of what the surface of the comet might look like.  2I/Borisov was a visitor from another planetary system that passed by our Sun in 2019, allowing astronomers a unique view of an interstellar comet. While telescopes on Earth and in space captured images of this comet, we don’t have any close-up observations of 2I/Borisov. It is therefore up to artists to create their own ideas of what the comet’s surface might look like, based on the scientific information we have about it. (ESO/M. Kormesser)

The team also found that the comet’s coma contains compact pebbles and grains of around 1mm and above.

Additionally, as 2I/Borisov neared the Sun the relative amounts of water and carbon they detected from it changed quite drastically.

“We found that the dust coma of Borisov consists of compact, millimeter-sized and larger pebble-like grains, which formed in the inner region near the central star,” Yang says. “We also found the cometary nucleus consists of components formed at different locations in its home system.”

“Our observations suggest that Borisov’s system exchanged materials between the inner regions and the outer regions that are far from the central star, perhaps due to gravitational stirring by giant planets much like in our own solar system.”

Bin Yang, ESO.

These characteristics indicate that 2I/Borisov formed by collecting materials from different locations in its own planetary system. It also imnplies that the system from which it originated likelty featured the exchange of materials between its inner and outer regions. Something that Yang says is also common in our solar system.

“So, it is possible that chaotic material exchanging processes are common phenomena for young planetary systems,” says Yang. “We want to know if other planetary systems form like our own. But we cannot study these systems to the level of their individual comets.”

“Interstellar objects represent the building blocks of planets around other stars. Comet Borisov provides a rare and valuable link between our own solar system and other planetary systems.”

The Journey of 2I/Borisov

2I/Borisov was first discovered by Gennedy Borisov, an amateur astronomer and telescope maker, in August 2019. It was only the second visitor from outside the solar system to be found within our planetary system. That means that as it passed the Sun it presented a unique opportunity to compare conditions in our small corner of the galaxy to those found in other planetary systems.

“2I/Borisov is quite a small comet and it didn’t get very close to the Earth and the Sun, so the emission from this comet is quite weak. We were happily surprised that we actually detected the thermal emission from this alien comet. Because of this detection, we are able to set constraints on the dust properties of this comet,” says Yang. “Comets in other planetary systems are simply too far away and too small to be seen by our telescopes.

“We are extremely lucky to find a comet that is from a planetary system far far away from us. Even more luckily, we managed to take many pictures and spectra of this alien comet during its short visit.”

Bin Yang, ESO.

As Yang points out, 2I/Borisov is only in our solar system for a short time before it must continue its interstellar journey, so the time available to astronomers to study it is limited. But, with interstellar visitors to the solar system believed to be fairly common, but difficult to spot, improving telescope technology could offer future opportunities to study other objects with similar interstellar origins.

Bagnulo points to both the upcoming Vera C Rubin telescope and ESA’s comet interceptor, set to launch in 2029, as future technology that could help us spot and investigate interstellar comets.

“We expect to detect at least one interstellar object per year,” Yang concludes. “So, we will have more opportunities to study alien materials.”

Amateur astronomer discovered a new sungrazing comet during last week’s eclipse

An amateur astronomer discovered a new sungrazer comet during last week’s solar eclipse, NASA reports. The body has been christened C/2020 X3 (SOHO).

Comet C/2020 X3 (SOHO) in the bottom left-hand corner with a composite image of the total eclipse (right).
Image credits: ESA/NASA/SOHO.

Sungrazing comets are like their brethren in every way except they pass very close to the Sun, sometimes within a few thousand kilometers of its surface. C/2020 X3 (SOHO) has been discovered by Worachate Boonplod on December 13 (a day before the eclipse) as part of the Sungrazer Project — a citizen science project which allows the public to look for comets in images from the Solar and Heliospheric Observatory, or SOHO.

New old comet

The sungrazer belongs to the Kreutz family of objects, NASA explains, which are the fragments of a larger comet that broke apart around one millennia ago. C/2020 X3 (SOHO) evaporated on approach towards the Sun, but other grazers still orbit around our star, the agency adds.

During its last moments, the comet was traveling at around 450,000 miles per hour, reaching as close as 2.7 million miles from the star’s surface. It was about 50 feet (15 meters) in diameter and disintegrated into dust on approach.

“But wait!”, you might say — “what eclipse?”. Last week saw the last eclipse of 2020, which was visible from a relatively narrow region in the Pacific, southern South America, and Antarctica. People in Chile, Argentina, and communities living in the southern Atlantic and Pacific oceans could see it as a total eclipse.

This is the 3,524th Kreutz sungrazer spotted by SOHO. None have yet been seen to actually hit the star, as they burn away in the lower corona (the Sun’s atmosphere) or pass around 31,000 miles (50,000 kilometers) away from its surface. SOHO works similarly to a solar eclipse, NASA adds, which is why it’s so good at spotting sungrazers. The telescope uses a solid disk to block out light coming in directly from the Sun, letting us analyze its dimmer atmosphere and close-by objects.

Surprisingly enough, comets can generate auroras too — in ultraviolet light

A team at the Southwest Research Institute (SwRI) has spotted the first comet we’ve ever seen to create an aurora in the ultraviolet spectrum.

Comet 67P. Image Courtesy of ESA/Rosetta/NAVCAM.

On Earth, auroras (or ‘polar lights’) are created when charged particles from the Sun hit those in our planet’s atmosphere. They form at the poles because that’s where the Earth’s magnetic field is weakest, allowing such particles to reach the atmosphere.

The discovery of a similar phenomena on a comet, bodies that lack our planet’s magnetic field, has researchers understandably excited.

A space first

“Charged particles from the Sun streaming towards the comet in the solar wind interact with the gas surrounding the comet’s icy, dusty nucleus and create the auroras,” said SwRI Vice President Dr. Jim Burch, in charge of the Ion and Electron Sensor (IES) instrument on board of the craft, in a statement.

“The IES instrument detected the electrons that caused the aurora.”

The IES is installed aboard the European Space Agency’s Rosetta spacecraft, which was launched back in 2004 and whose mission ended in 2016. Together with Philae, its lander module, Rosetta was the first of our probes to fly alongside a frozen comet (67P/Churyumov–Gerasimenko) as it hurdled towards the Sun, observing how it behaved along the way.

Now, data from Rosetta has revealed ultraviolet auroras around 67P, the first ever seen on a comet. These auroras are produced by charged particles interacting with the ‘coma’, the bubble of gas that is created from and encases the comet. This interaction excites the gases enough to make them glow in ultraviolet (UV) light.

Dr. Joel Parker, a member of SwRI who handled data from the Alice far-ultraviolet (FUV) spectrograph on Rosetta, recounts that at first, the team believed they were seeing 67P’s ‘dayglow’, a well-documented phenomenon created by this bubble of gas interacting with photons (light). But they soon realized that this wasn’t the case.

“We were amazed to discover that the UV emissions are aurora, driven not by photons, but by electrons in the solar wind that break apart water and other molecules in the coma and have been accelerated in the comet’s nearby environment,” he explains.”The resulting excited atoms make this distinctive light.”

The findings show that its possible for auroras to form around comets, despite their lack of a magnetic envelope. The techniques developed by the team to integrate data from several devices and discover these auroras can serve us to find similar phenomena on other comets in the future.

The findings will been published in the journal Nature Astronomy.

Hubble spots our second interstellar visitor — a comet

NASA’s Hubble Space Telescope has just taken a peek at the second interstellar object to visit the solar system — a comet.

Image credits NASA / ESA / J. DePasquale (STScI).

Based on its current speed and trajectory, 2I/Borisov likely came from outside our solar system. It is the second such object after the asteroid ‘Oumuamua (identified in 2017). However, the two are very different beasts — while ‘Oumuamua was a rocky, solid body, 2I/Borisov is a comet. The image taken by Hubble is the best look we’ve had at 2I/Borisov so far and reveals a body of dust around a central core (which is too small to be seen in the image).

It cometh second

Whereas ‘Oumuamua appeared to be a rock, Borisov is really active, more like a normal comet. It’s a puzzle why these two are so different,” said David Jewitt of the University of California, Los Angeles (UCLA), leader of the Hubble team who observed the comet.

Being the second interstellar object we’ve found so close to home, researchers are very keen to study the properties and nature of 2I/Borisov. Its chemical composition, structure, and the dust around it are products of its host star system and can teach us about how they form. We won’t know for sure without further observation, but so far, the comet’s properties appear to be very similar to those in the Solar System.

The comet was 260 million miles from Earth when Hubble took its picture. It is on a hyperbolic path around the Sun, currently moving at around 110,000 miles per hour. Its closest approach will be on Dec. 7, 2019, when it will be twice as far from the Sun as Earth. By mid-2020, NASA adds, it will make its way past Jupiter and onto interstellar space.

“It’s traveling so fast it almost doesn’t care that the Sun is there,” said Jewitt.

2I/Borisov was first discovered by Crimea-based amateur astronomer Gennady Borisov on Aug. 30, 2019. After a week of observations, the International Astronomical Union’s Minor Planet Center and the Center for Near-Earth Object Studies at NASA’s Jet Propulsion Laboratory in Pasadena, California, confirmed that it came from interstellar space. Future Hubble observations of 2I/Borisov are planned through January 2020, with more being proposed.

Newfound comet could be an interstellar object, experts argue

A newly discovered comet heading towards the orbit of Mars has scientists working to confirm whether it came from outside the solar system, a likely prospect that would make it the second time astronomers see an interstellar visitor on its way past the sun.


The comet, first detected by Crimean astronomer Gennady Borisov, follows a highly curved path barreling in the sun’s direction at unusually high speeds, evidence that it originated beyond the solar system.

“We’ve been scrambling here at the University of Hawaii to get observations to make position measurements,” said Karen Meech, an astronomer at the university whose team concluded that the object classifies as a comet. “Every time a new comet is discovered, everybody starts to try and get data so that you can get the orbit.”

An apparent amalgam of ice and dust, the comet is expected to make its closest approach to the sun on December 8, putting it 190 million miles (300 million km) from Earth, on a route believed unique to such objects of interstellar origin.

The comet is now heading toward the inner solar system and will enter it on Oct. 26 from above at roughly a 40-degree angle relative to the ecliptic plane. That’s the plane in which the Earth and planets orbit the Sun.

It was established as being cometary due to its fuzzy appearance, which indicates that the object has a central icy body that is producing a surrounding cloud of dust and particles as it approaches the Sun and heats up.

Once confirmed interstellar, the comet – dubbed C/2019 Q4 by astronomers – would become only the second such body ever observed by scientists. The first was a cigar-shaped comet dubbed ‘Oumuamua – a name of Hawaiian origin meaning a messenger from afar arriving first – that sailed into our planetary neighborhood in 2017.

“It’s going to be a nice Christmas comet,” says astronomer Michele Bannister of Queen’s University Belfast in Northern Ireland. “We’ll be able to observe it for probably a year, which is really different from ‘Oumuamua.”

Unlike ‘Oumuamua, which visited the solar system for only a week, the newfound comet will linger near Mars’ orbit for almost a year, giving scientists ample time to characterize its chemical signatures and seek further clues about its origin.

“The high velocity indicates not only that the object likely originated from outside our solar system, but also that it will leave and head back to interstellar space,” said Davide Farnocchia, an astronomer at NASA’s Jet Propulsion Laboratory in California.

Comet-inspired reactor could create oxygen for astronauts

When it comes to space, oxygen has been famously known to be in short supply. This is why it was a very pleasant surprise when two researchers at the California Institute of Technology found a way to produce some.

Konstantinos P. Giapis with his reactor that converts carbon dioxide to molecular oxygen. Credit: Caltech.

In 2015, the European Space Agency’s Rosetta spacecraft unexpectedly found abundant levels of molecular oxygen in Comet 67Ps atmosphere. Molecular oxygen in space is highly unstable, as oxygen prefers to pair up with hydrogen to make water, or carbon to make carbon dioxide. When oxygen was detected streaming out of the comet, it was believed that the gas had been locked inside the comet for billions of years.

However, in 2017, Caltech researchers proposed that the oxygen was actually created by other compounds slamming into the comet at high speeds. After water or carbon dioxide are discharged from the comet, solar winds accelerate them back into the comet, which creates molecular oxygen.

Now Caltech scientists have created a reactor to reproduce this reaction originally found in outer space. Such technology is appealing, as it could provide future astronauts on Mars a way to generate their own air. It could even be utilized on our home planet to combat our little carbon dioxide problem. The process would remove CO2 from the atmosphere, converting it into O2, giving humans a leg-up in the war against climate change.

It works by crashing CO2 onto the inert surface of gold foil. The foil cannot be oxidized and theoretically should not produce molecular oxygen. However, through the experiment, O2 continued to be emitted from the gold surface. This meant that both atoms of oxygen come from the same CO2 molecule, effectively splitting it in extraordinary style.

“At the time we thought it would be impossible to combine the two oxygen atoms of a CO2 molecule together because CO2 is a linear molecule, and you would have to bend the molecule severely for it to work,” says Konstantinos P. Giapis, a professor of chemical engineering at Caltech. “You’re doing something really drastic to the molecule.”

Credit: Caltech.

Most chemical reactions require energy, which is most often provided as heat. However, Giapis’s research shows some unusual reactions can occur by providing kinetic energy. When water molecules are shot like extremely tiny bullets onto surfaces containing oxygen, such as sand or rust, the water molecule can rip off that oxygen to produce molecular oxygen.

“In general, excited molecules can lead to unusual chemistry, so we started with that,” Tom Miller, a professor of chemistry at Caltech, says. “But, to our surprise, the excited state did not create molecular oxygen. Instead, the molecule decomposed into other products. Ultimately, we found that a severely bent CO2 can also form without exciting the molecule, and that could produce O2.”

The device the Caltech team devised works like a particle accelerator. It converts carbon dioxide molecules into ions by giving them a charge and then fast-tracking them using an electric field, though at drastically lower energies than you’ll find in a particle accelerator. The device generates only one or two oxygen molecules for every 100 carbon dioxide molecules.

“You could throw a stone with enough velocity at some CO2 and achieve the same thing. It would need to be traveling about as fast as a comet or asteroid travels through space,” said Giapis but stresses this is not the final product. “Is it a final device? No. Is it a device that can solve the problem with Mars? No. But it is a device that can do something that is very hard,” he says. “We are doing some crazy things with this reactor.”

The study was published in the journal Nature Communications

A Hubble Space Telescope view of asteroid 6478 Gault, showing two comet-like tails of debris. Credit: European Southern Observatory.

Astronomers spy self-destructing asteroid with a twin comet-like tail

A Hubble Space Telescope view of asteroid 6478 Gault, showing two comet-like tails of debris. Credit: European Southern Observatory.

A Hubble Space Telescope view of asteroid 6478 Gault, showing two comet-like tails of debris. Credit: European Southern Observatory.

Almost 214 million miles (344 million km) from the sun, an asteroid is doing its best comet-like impression. Astronomers at the University of Hawaii have discovered an asteroid that is spinning itself into pieces, generating two debris tails of dust in the process.

First discovered in 1988, the first signs that the asteroid was self-destructing came on January 5. Using NASA’s Hubble Space Telescope, along with a variety of ground-based instruments in Hawaii, Spain, and India, astronomers found two debris tails trailing 6478 Gault in the main asteroid belt between Mars and Jupiter.

“This self-destruction event is rare,” Olivier Hainaut, of the European Southern Observatory in Garching, Germany, and co-author of the report said. “Active and unstable asteroids such as Gault are just now being detected because of new survey telescopes that scan the entire sky, which means asteroids that are misbehaving such as Gault cannot escape detection anymore.”

The observations are the first pieces of evidence of Gault’s misbehavior and suggest that asteroids are dynamic and can ultimately disintegrate due to the long-term subtle effect of sunlight, which can slowly spin them up until they begin to shed material. In Gault’s case, the asteroid is doing a speedy rotation every two hours, so fast that Gault is flinging material off its surface and into the void.

“Gault is the best ‘smoking-gun’ example of a fast rotator right at the two-hour limit,” said the University of Hawaii’s Jan Kleyna. “It could have been on the brink of instability for 10 million years. Even a tiny disturbance, like a small impact from a pebble, might have triggered the recent outbursts.”

Hubble revealed the tails to be narrow streamers, indicating that the dust was released in short bursts, lasting anywhere from a few hours to a few days. These sudden events puffed away enough debris to make a “dirt ball” approximately 500 feet (150 meters) across if compacted together. One tail was found to be approximately 500,000 miles (800,000 km) long by 3,000 miles (4,800 km) wide. The smaller tail spans about 125,000 (200,000 km) long.

Watching an asteroid come unglued like Gault gives astronomers the opportunity to study the makeup of asteroids without sending a spacecraft for samples. Analyzing an asteroid’s ingredients as they are spread out into space can offer astronomers a glimpse into planet formation in the early solar system.

“We didn’t have to visit Gault,” explained Hainaut. “We just had to look at the image of the streamers, and we can see all of the dust grains sorted neatly by size. All the large grains (about the size of sand particles) are close to the object and the smallest grains (about the size of flour) are the farthest away, because they are being pushed fastest by pressure from sunlight.”

3D meteorite level.

What’s the difference between an asteroid and a meteorite?

On June 30th, 1908, the boreal forests of Tunguska, Siberia, were shaken (and subsequently flattened) by a massive explosion. It wasn’t man-made — an asteroid pierced our planet’s atmosphere and exploded before hitting the surface.

3D meteorite level.

Artistic rendering of a meteorite.
Image via Pixabay.

This explosion, known as the Tunguska event, would make history. It was the largest impact event humanity has ever witnessed first-hand and would lead the UN to declare June 30th the International Asteroid Day.

While definitely awe-inspiring, the event didn’t lead to the massive loss of life that, say, the Chixulub Impactor caused (that’s the pebble that killed the dinosaurs). So why did one space-rock kill off the largest beasts to ever roam the Earth, while another merely flattened 2,000 square kilometres (770 square miles) of forest without causing a single human death? Well, the secret is all in the definition. Today, we’ll take a look at that simple yet oh so important distinction between an asteroid and a meteorite.

What is an asteroid?

The word itself gives us a glimpse into the nature of asteroids. “Aster” is the ancient Greek word for ‘star’, and the suffix “-oid” is used to show an incomplete or imperfect resemblance to the root word. “Asteroid”, therefore, means ‘star-like’ or, taken more literally, ‘star-like, but not quite’.

Keep in mind that for the ancient Greeks looking up into the night sky, planets and stars all looked the same; ‘aster’, therefore, can be understood as both ‘star’ and ‘planet’.

Vega asteroids.

Artist’s concept of an asteroid belt around the star Vega. Oumuamua, the first object to pass through our solar system that was confirmed to come from outside it — originates from this system.
Image credits NASA / JPL-Caltech.

Asteroids are chunks of space rock ranging from one meter to almost a thousand kilometers in diameter. The larger ones may rightfully be considered minor planets (or dwarf planets/planetoids). Ceres is a good example of this latter category, and the largest known asteroid. These large ones closely resemble planets: they’re roughly spherical and have at least partly-differentiated core structures. They’re generally considered baby planets that didn’t quite make it to adult status.

Most asteroids, however, are quite petite. They also don’t seem to prefer a particular shape. To the extent of our knowledge, they either formed from the primordial matter of a stellar system or via subsequent impacts between its first rocky bodies. Most asteroids in our neighborhood today make a home in the asteroid belt (surprising, I know).

So, to recap: asteroids are chunks of rock or metal (or both) in space. They’re mostly made up of telluric elements (such as carbon, metals, and silica), which tend to be quite resilient. They’re either planets that couldn’t grow large enough or their shattered remnants. Most known ones hang out in the asteroid belt between Mars and Jupiter, but they can take on all sorts of orbits (or none at all!)

What is a meteorite?

Hoba meteorite.

The Hoba meteorite in Grootfontein, Namibia, is the largest meteorite known to have landed on Earth. Estimated to weigh around 60 tonnes, it has never been moved from the spot it was discovered in. Hoba is currently a very visited touristic attraction.
Image credits Sergio Conti / Wikimedia.

A meteorite is any space-borne body that enters a planet’s or moon’s atmosphere, survives the violent trek through it, impacts the surface, and leaves behind solid pieces of material. The name comes from the ancient Greek words “meta” and “aerio”, which put together roughly translate to ‘something hanging up in the air’.

Meteorites start their life as meteoroids (small meteors) or asteroids. On contact with an atmosphere, meteorites experience immense friction, causing them to spontaneously combust (at up to 3,000 degrees Fahrenheit, or 1,649 degrees Celsius). These fireballs — colloquially called shooting or falling stars — are meteors.

The life of a meteor is short — and hellish. The friction they experience is enough to raise surface temperatures beyond the material’s boiling point, vaporizing it layer by layer. In fact, it’s enough to break apart its (and the atmosphere’s) constituent molecules into ionized particles (basically plasma), which then recombine, releasing energy as light. This is the tail you see on a shooting star.

Meteor over Sardinia.

Meteor over Sardinia, seen on the 8th of May 2016.
Image credits Migebuff / Wikimedia.

The extreme violence of the final impact generally shaves off much of a meteor’s mass — the remaining kernel is our meteorite. Keep in mind that geologists generally call impactors large enough to create a crater ‘bolides’, while astronomers tend to prefer ‘meteorite’.

Depending on chemical composition, angle and speed of atmospheric entry, as well as sheer happenstance (whether it breaks apart or not), a meteor needs to range in size between a marble and a basketball for even a tiny portion of it to reach our planet’s surface.

Meteorites under 2mm (0.07in) in diameter are called micrometeorites. Meteorites that impact celestial bodies apart from Earth (and thus don’t necessarily pass through an atmospheric layer, such as those hitting the Moon) are called extraterrestrial meteorites.

As a side note, these burning chunks also spawned the associated term ‘meteorology’, or ‘the knowledge of things happening up in the air’, the branch of atmospheric sciences involved heavily in the study and forecasting of weather events.

So… what’s the difference between them?

As a general guideline, most meteorites are asteroids — but very few asteroids are meteorites.


Ceres, for example, is a moon and an asteroid. We do NOT want it to be a meteorite, too!
Image credits NASA / JPL-Caltech / UCLA/ MPS / DLR / IDA.

The definitions tend to overlap a little. Let’s take size, for example. An astronomer will call any of these space projectiles ranging between a molecule and a chunk several hundred feet wide (usually up to 100m / 330ft in diameter) a meteoroid. Anything larger than that, generally, is considered an asteroid.

However, that leaves out chemistry, which is also a hard delineator for what is (and isn’t) an asteroid. Comets are globs of ice and dust formed in the freezing corners of the cosmos (i.e. outside of solar systems). They also have a little pocket of atmosphere around them (a distinctive feature for comets), generated by evaporation from this ice. Their interaction with heat and particles generated by stars is what creates those long, elegant plumes that are quintessentially comet-y.

Comets can and do fly towards planets and moons. The beefier ones also generally make it through any atmospheric layer and impact the surface. What makes comets generally fall short of being termed ‘meteorites’ is that they’re made up of volatile materials that don’t survive post-impact. However, some do — and also leave behind traces of their impact in the form of impact glass or diamonds. While definitely traces of impact, it can be seen as a technicality to consider such elements remnants of the impacting body itself. I personally do. So, following the impact-and-debris definition, I’d consider comets impacting the surface to be meteors as well.

And herein lies the difference. To be a meteorite, one needs to impact a planet or moon and leave behind solid debris. To paraphrase Iain Banks (my favorite author) the meteorite only lives as it is falling. For asteroids, it’s sufficient to be. Have the right chemical make-up, don’t be too tiny, don’t sublime too much when around stars, and voila! You’re an asteroid.

Most asteroids are nice and never impact any planets or moons. The overwhelming majority of them, actually, are content to orbit around in their asteroid belts or on whatever path they’re set on. But we should never take their absence for granted; it only takes one to come visiting for humanity to become a thing of the past.

Just ask the dinosaurs.


Building blocks of life can spontaneously form in outer space

Space may be the final frontier, but it may have also been the first.


Image via Pixabay.

Researchers at NASA’s Ames Research Center found new evidence in support of the view that asteroids carried the basic ingredients of life to Earth. In a new study, they report that such compounds can spontaneously form in the conditions of outer space with substances commonlt found the interstellar medium.

From whence we came. Maybe

We actually don’t know that much about how life started on Earth. In fact, we don’t even know if life started on Earth — at least, not its constituent parts. Two main theories compete in this regard. One holds that life emerged in hot springs or deep-sea thermal vents because such areas are rich in the right ingredients. The other states that those ingredients formed up there (way up there) and then crash-landed on the planet on the back of meteorites or comets.

The Ames Research Group team found evidence supporting the latter. They found that one of the fundamental building blocks of life — sugars — can and will spontaneously form in outer space. Sugars are important both from a nutritional value (they pack a lot of energy) as well as a biochemical one: 2-deoxyribose, for example, is a fundamental component of DNA (and also a sugar).

In a lab setting mirroring conditions in outer space, the team managed to spontaneously create 2-deoxyribose. The team cooled a sample of aluminum substrate in a freezer and cooled it down to nearly absolute zero. Afterward, they placed the sample in a vacuum chamber; all in all, this rig was a close simulation of conditions in deep space, they report.

Next, the researchers pumped small quantities of a water and methanol gas mixture similar to that found in the interstellar medium (to simulate its chemical makeup) and blasted the whole thing with UV light (to simulate radiation levels in outer space).

Initially, the test seemed to be a dud — only water ice formed on the sample. After a while, however, the strong UVs melted it down, and subsequent chemical analysis revealed that a small quantity of  2-deoxyribose had formed along with some other sugars. Fresh on the scent, the team then analyzed samples from several carbonaceous meteorites. They found traces of alcohols and deoxysugar acids on these space rocks which.

Although that’s not exactly 2-deoxyribose, the team notes their samples were drawn from a small number of meteorites. It’s quite possible, they add, that others would carry traces of these substances.

The findings add more weight to the to the theory that life got jump-started by space-stuff. However, that isn’t to say it’s definitive proof, or that the two scenarios didn’t take place at the same time, or in tandem. It is, however, a good indicator that the chemical building blocks of life are out there and, given the right environment, they can lead to life.

The paper “Deoxyribose and deoxysugar derivatives from photoprocessed astrophysical ice analogues and comparison to meteorites” has been published in the journal Nature Communications.

Phosphate compounds may have arrived on Earth delivered by comets, such as comet 67P/Churyumov-Gerasimenko. Credit: ESA/Rosetta/NAVCAM

Key ingredient for life on Earth may have come from outer space

Phosphates, essential ingredients for DNA-based life forms, may have originated from space, according to a new study that recreated the formation of the molecules in a laboratory setting. The life-seeding phosphates would have then made their way to Earth through asteroids and comets that impacted the planet billions of years ago.

Phosphate compounds may have arrived on Earth delivered by comets, such as comet 67P/Churyumov-Gerasimenko. Credit: ESA/Rosetta/NAVCAM.

Without phosphates and diphosporic acid, living things wouldn’t be able to synthesize DNA. They are the main components of chromosomes, thread-like structures in which the DNA is packaged. Phosphorus is also part of adenosine triphosphate (ATP), which stores energy in the cell and powers cellular processes. Bones and teeth are also made up of phosphorus.

A long-standing debate among scientists is whether these chemical compounds were forged on Earth or someplace else in the universe, hitching a ride on cosmic bodies that collided with our planet.

Although the debate sounds impossible to solve, researchers at the University of Hawaii at Manatoa have now offered compelling evidence that phosphates can be generated in space.

For their experiment, the researchers worked with the chemical phosphine, which is derived from phosphorus and can be found in the atmospheres of planets such as Jupiter or Saturn, but also those of comets such as the famous 67P/Churyumov-Gerasimenko, explored by the Rosetta spacecraft in 2016.

First, the team recreated icy grains — the kind typically found in interstellar space — in a vacuum chamber where the temperature sat  just 5 degrees Kelvin above absolute zero (-450°F/-267.7°C). Then, they added water, carbon dioxide and — very carefully because it is highly toxic — phosphine. Finally, the researchers fired ionized radiation — the kind found in cosmic rays — at this, triggering chemical reactions that formed phosphoric acid and diphosphoric acid.

“On Earth, phosphine is lethal to living beings,” said Andrew Turner, lead author of the study in Nature Communications, in a statement. “But in the interstellar medium, an exotic phosphine chemistry can promote rare chemical reaction pathways to initiate the formation of biorelevant molecules such as oxoacids of phosphorus, which eventually might spark the molecular evolution of life as we know it.”

In deep space, it’s reasonable to assume such nanoparticles became embedded in large objects like asteroids and comets, which would have eventually made their way to Earth.

“Since comets contain at least partially the remnants of the material of the protoplanetary disk that formed our solar system, these compounds might be traced back to the interstellar medium wherever sufficient phosphine in interstellar ices is available,” said Cornelia Meinert of the University of Nice.

The findings appeared in the journal Nature Communications.

NASA’s brand new TESS telescope is already sending back impressive footage

NASA’s Transiting Exoplanet Survey Satellite (TESS) started its scientific activity on July 25, but, even before that, TESS managed to snap some awesome images of a passing comet — only discovered a month ago.

Image credits: Massachusetts Institute of Technology/NASA’s Goddard Space Flight Center.

The comet is named C/2018 N1 and is located some 48 million kilometers (29 million miles) from Earth, in the southern constellation Piscis Austrinus — the Latin name for “southern fish”. The comet can be seen moving right to left, orbiting the Sun, leaving behind a “tail” — which consists of gases carried away from by an outflow from the Sun called the solar wind, according to NASA.

But the comet isn’t the only interesting thing visible in the images, which also feature asteroids and stars. If you look closely, you can see some stars shifting from white to black and to white again. This comes as a result of image processing, which highlights variable stars. These stars change brightness either as a result of pulsation, rapid rotation, or by eclipsing binary neighbors.

Artistic depiction of the TESS telescope. Image credits: NASA.

TESS’ main job, however, isn’t to keep an eye out for comets and variable stars. In a two-year survey of the solar neighborhood, TESS will monitor more than 200,000 stars for temporary drops in brightness caused by planetary transits. This is the most common way of detecting a planet. Since planets don’t have their own light, it’s difficult to see them directly so, instead, they look at stars and look for dips in its luminosity, which can be indicative of a planet passing between the star and the Earth. The nature of the dip can then be used to determine certain parameters of the planet. The vast majority of the 3,815 confirmed exoplanets have been discovered using this method.

TESS is the first-ever spaceborne all-sky transit survey. It will scout the sky, looking for planets ranging from Earth-sized to gas giants, around a wide range of stellar types and orbital distances, primarily focusing on the brightest stars in Earth’s vicinity. No ground-based survey can achieve this feat, due to atmospheric perturbations.

Since the comet footage, TESS has already started its main activity. Hopefully, it won’t be long until the first results start coming in, and we have a new batch of exoplanets to study and understand.

You can read more about TESS on its NASA website, and follow its news on Twitter. It’s worth it.


Comet 67P harbors oxygen molecules as old as the Solar System

Molecular oxygen found on the comet 67P/Churyumov-Gerasimenko isn’t produced on the surface — it comes from the early days of the Solar System.


Mosaic of four images taken by Rosetta’s navigation camera (NAVCAM) on 19 September 2014 at 28.6 km (17.8 mi) from the centre of comet 67P/Churyumov–Gerasimenko.
Image credits ESA / Rosetta / NAVCAM.

Between August 2014 and September 2016, the European Space (ESA) Agency’s Rosetta craft tagged along with the comet  67P/Churyumov-Gerasimenko as it was trekking around the Sun. The mission also saw a probe delivered to the comet’s surface.

Among other things, the ESA wanted to use Rosetta to study the comet’s coma — the nebulous envelope around the nucleus of a comet. This structure is created by ice subliming — turning from a solid directly into a gas — on the comet’s surface under the sun’s rays. Rosetta’s analysis of the coma revealed that it contains water, carbon monoxide and dioxide (all compounds we were expecting to find), but also molecular oxygen.

Retro oxygen

Molecular oxygen is composed of two oxygen atoms tied together by a covalent bond. Here on Earth, it’s produced by plants via photosynthesis, but researchers are well aware that oxygen is abundant in many places of the universe — we’ve detected molecular oxygen around some of Jupiter’s moons, for example. By mass, oxygen is the third-most abundant element in the universe, after hydrogen and helium — but finding it around a comet was surprising, to say the least.

With the finding also came questions regarding the origin of this molecular oxygen. Some researchers suggested that it might be produced on the comet’s surface under the action of charged ions in the solar wind.

A new paper published by members of the Rosetta team has analyzed data beamed back by the craft to get to the bottom of the issue. The research, led by researchers from the Imperial College London, found that the proposed ionic mechanism for molecular oxygen generation couldn’t account for levels of this molecule observed in the coma. This would mean that the oxygen molecules Rosetta stumbled upon are primordial — meaning they were already fully formed as the comet itself quickened during the early days of the Solar System 4.6 billion years ago.

“We tested the new theory of surface molecular oxygen production using observations of energetic ions, particles which trigger the surface processes which could lead to the production of molecular oxygen,” said lead author Mr Kevin Heritier. “We found that the amount of energetic ions present could not produce enough molecular oxygen to account for the amount of molecular oxygen observed in the coma.”

The findings don’t rule out oxygen generation at the surface level of 67P — but that the majority of the oxygen in the comet’s coma is simply not produced through such a process.

While there are other theories regarding the origin of 67P’s oxygen, the team didn’t address them in any way, either to confirm or infirm them. So far, however, they say that the primordial oxygen theory is the one which fits available data best. This is further supported by other theoretical work that treats the formation of molecular oxygen in dark clouds and the presence of molecular oxygen in the early Solar System, they add. In the team’s model, preexisting molecular oxygen froze into tiny grains that later clumped together, attracted more material, and eventually got bound up in the comet’s nucleus.

The paper “On the origin of molecular oxygen in cometary comae” has been published in the journal Nature Communications.

Just 15 minutes after its closest approach to Pluto on July 14, 2015, NASA's New Horizons spacecraft looked back toward the sun and captured a near-sunset view of the rugged, icy mountains and flat ice plains extending to Pluto's horizon. Credit: NASA.

Pluto might have been formed by a billion comets

Pluto might not officially be a planet anymore, but that doesn’t make it’s any less interesting.

One of the most important objects of inquiry regarding the distant dwarf planet has to do with its formation. Now, thanks to unprecedented observations carried out by spacecraft like New Horizons and Rosetta, scientists are coming close to understanding how Pluto came to be. One of the craziest, but still plausible, Pluto formation theories was recently unveiled by researchers at the Southwest Research Institute (SwRI). They suggest that Pluto might have been formed by one billion comets that came together.

Just 15 minutes after its closest approach to Pluto on July 14, 2015, NASA's New Horizons spacecraft looked back toward the sun and captured a near-sunset view of the rugged, icy mountains and flat ice plains extending to Pluto's horizon. Credit: NASA.

Just 15 minutes after its closest approach to Pluto on July 14, 2015, NASA’s New Horizons spacecraft looked back toward the sun and captured a near-sunset view of the rugged, icy mountains and flat ice plains extending to Pluto’s horizon. Credit: NASA.

The solar system‘s planets formed by accretion of material from enormous discs that surround the early Sun. The matter inside the rapidly spinning disk around the parent star simply gathers and forms clumps, steadily accumulating until these turn into asteroids, comets, planets, and moons.

Pluto was always thought to have formed much in the same way. However, geochemist Christopher Glein and colleagues at SwRI’s Space Science and Engineering Division found it odd how the dwarf planet and the famous Comet 67P/Churyumov-Gerasimenko — the one where ESA landed a probe in 2014 — share so much of their chemical makeup. For instance, Pluto’s nitrogen-rich Sputnik Planitia is unnaturally similar to Comet 67P.

Just as water is the main driving force that shapes Earth’s surface, so is nitrogen for Pluto. Due to its low viscosity, nitrogen flows like glaciers on Earth, eroding the bedrock and, in the process, altering the landscape. And there’s so much nitrogen on Pluto. Earth’s atmosphere is made up of 78% nitrogen, but Pluto’s, which is far colder, is 98% nitrogen. That’s an unusual proportion of nitrogen, both at the surface and in the atmosphere, which is not easily explained by the conventional planetary formation theory. Instead, what seems to connect the dots is a huge comet frenzy.

“We’ve developed what we call ‘the giant comet’ cosmochemical model of Pluto formation,” Glein said in a statement.

“We found an intriguing consistency between the estimated amount of nitrogen inside the glacier and the amount that would be expected if Pluto was formed by the agglomeration of roughly a billion comets or other Kuiper Belt objects similar in chemical composition to 67P, the comet explored by Rosetta.”

Real photo of 67P/Churyumov-Gerasimenko. Credit: NAVCAM/ROSETTA/ESA.

Real photo of 67P/Churyumov-Gerasimenko. Credit: NAVCAM/ROSETTA/ESA.

The researchers got their data from the Rosetta probe that reached comet 67P and NASA’s New Horizons mission, which flew by Pluto in July 2015. In the new ‘giant comet’ cosmochemical model, Pluto’s initial chemical makeup is inherited from comet building blocks but was later changed by liquid water.

But this is far from being the last word on the matter. Another competing model suggests that Pluto coalesced from cold ices with a chemical composition closer to that of the sun

“This research builds upon the fantastic successes of the New Horizons and Rosetta missions to expand our understanding of the origin and evolution of Pluto,” said Glein.

“Using chemistry as a detective’s tool, we are able to trace certain features we see on Pluto today to formation processes from long ago. This leads to a new appreciation of the richness of Pluto’s ‘life story,’ which we are only starting to grasp.”

The new study is set to appear in the journal Icarus. It is already available online on the pre-print server arXiv.

Watch: real footage of cosmic particle ‘snow’ on comet 67P

It looks like a winter wonderland scene from an old black and white film but — don’t be fooled — what you’re seeing is real footage from the surface of the comet 67p/Churyumov-Gerasimenko. These images were captured by the European Space Agency’s Rosetta probe over the course of 25 minutes on the 1st of June, 2016, and processed by an awesome human who posted the whole thing on twitter.

The raw images were made with Rosetta’s OSIRIS, or Optical, Spectroscopic, and Infrared Remote Imaging System. What we’re seeing in the foreground is the comet’s surface, as seen by the probe from a distance of several kilometers. In the background, you can see stars belonging to the constellation Canis Major.

What looks like snow here are actually cosmic rays (charged subatomic particles), which register as streaks of light as they hit the camera’s sensor. It’s true, however, that there is some actual snow in the footage — specks of dust and ice.

The Rosetta spacecraft and its lander, Philae, reached 67P in 2014 after a 10-year round-trip journey of four billion miles.  The probe crashed into the comet’s surface in 2016.

Rho Ophiuchi.

Biomarker molecule discovered “in abundance” around alien star, but still no life

A large number of biomarker molecules have been found around a young star in the Rho Opiuchi region of space. The find sadly casts doubt to the substance’s value as a biomarker, but does further our understanding of star-birth.

Rho Ophiuchi.

The Rho Ophiuchi stellar nursery viewed by ESA’s Herschel observatory. The image combines Herschel observations at 70 microns (blue), 160 microns (green) and 250 microns (red), and spans 7.9°by 4.6°; north is up and east to the left.
Image credits ESA.

The European Space Agency (ESA) has some good and bad news to share with all of us today. The good news is that they’ve found a biomarker molecule — a byproduct of biological activity — in abundance in a comet and around a young, alien binary star. Pack those hooray’s back in, though, because there’s a catch. Instead of indicating the presence of extraterrestrial life, this discovery instead casts doubt on this substance’s merits as a biomarker, signaling that it’s probably not as clear-cut a sign of life as we once thought it was.

CH3Cl giveth, CH3Cl taketh away

Using a telescope to spot aliens — whether they be microscopic or human-sized — throughout the vast stretches of nothingness that is outer space is obviously not very doable. Instead, scientists have to rely on indirect methods of assessing a planet’s likelihood of harboring life. One of these methods involves checking for certain chemical compounds that are by-products of organic processes. We call them biomarkers, and any way you can detect them, from soil or water samples taken by rovers to atmospheric analysis by telescopes or spacecraft, is fair game: if you find a biomarker, the theory goes, life can’t be far away.

One of these biomarkers, in fact the most common one here on good old Earth, is methyl chloride (CH3Cl). It belongs to a class of chemical compounds known as organohalogens (organic compounds that also carry at least one atom in the halogen family — fluorine, chlorine, bromine, or iodine — and is also known by the name of chloromethane. For all intents and purposes, it’s exactly like methane (the stuff farts are made of), only one of the molecule’s hydrogen atoms gets swapped for a chlorine one. Since it’s mostly produced through biological processes, we use it as a biomarker.

Recently, however, the ALMA (Atacama Large Millimeter/Submillimeter Array) telescope in Chile found methyl chloride around IRAS 16293-2422, a binary star system some 400 light-years away from Earth, in the Rho Ophiuchi star-forming region. This marks the first time any organohalogen has been picked up in space. Sadly, this isn’t the beginning of an interstellar friendship — rather, the discovery erodes methyl chloride’s reliability as a biomarker.

Comet delivery to planets.

In addition to inheriting ingredients during the planet-forming processes, comets are also believed to have delivered some of the basic ingredients needed for life to Earth, leading to life as we know it today.
Image credits ESA.

Its presence around such a young star couple suggests that this substance may also be released during the planetary formation phase of a star system. To get a better idea of how it came about, the team turned to comets, bodies which can be used as ‘time capsules’ from the birth of stars, as they preserve the original chemical composition of the clouds of dust and gas solar systems are made of.

Their comet of choice was Comet 67P/Churyumov–Gerasimenko, handily visited by ESA’s Rosetta mission between 2014 and 2016. Sifting through the data collected during the mission, the team found it also contained an abundance of methyl chloride, further strengthening the theory that it represents a by-product of the planetary formation phase instead of the presence of life. The peak for methyl chloride was recorded in May 2015, when Churyumov–Gerasimenko was approaching the Sun.

“We found it but it is very elusive, one of the ‘chameleons’ of our molecule zoo, only present during short times when we observed a lot of chlorine,” says Kathrin Altwegg, principal investigator of the project.

So no alien life right now — bummer. But that doesn’t mean the search is off — actually, we now have an even better idea of what to look for. This may just be the lucky break we needed.

Artist's impression of 288P.

Hubble snaps the first binary-asteroid comet we’ve ever seen

Is it an asteroid? Is it a comet? It’s both and more. A group of astronomers recently published a paper describing one of the more unusual objects hidden in the asteroid belt. Known as 288P, this asteroid couple orbits each other while also exhibiting comet-like features.

Artist's impression of 288P.

Artist’s impression of 288P.
Image credits ESA / Hubble Images and Videos.

Back in September 2016, 288P was making its closest recorded approach to the Sun. Scientists naturally giggled in anticipation, since 288P looked like a comet and we don’t get to see belt-borne comets in this corner of space very often. Understanding how they form and behave could help teach us about the birth of the Solar System at large. So drawing on the NASA/ESA Hubble Space Telescope, the group of astronomers, led by Max Planck Institute for Solar System Research scientist Jessica Agarwal, seized this opportunity to take a detailed look at the body.

What they found is so far unique: 288P is not a single body, but two asteroids orbiting each other and exhibiting comet-like features, including a bright coma and a long tail. It is the first time we’ve even seen a binary asteroid body that’s also a comet.

Asteroids cometh

The snaps Hubble took of 288P showed that it’s actually a duo of asteroids, of almost the same size and mass, orbiting at about 100 kilometers (62.1 miles) from one another. This observation was crucial in itself, as by recording their orbits the team could calculate their masses. However, the data Hubble recorded also helped reveal ongoing activity in the binary system, the team reports, offering a glimpse of the body’s past.

“We detected strong indications of the sublimation of water ice due to the increased solar heating — similar to how the tail of a comet is created,” Agarwal explains.

“Surface ice cannot survive in the asteroid belt for the age of the Solar System but can be protected for billions of years by a refractory dust mantle, only a few metres thick.”

Starting from this, the team concluded that 288P has been in its current binary form for about 5,000 years now. The most probable cause of formation is “a breakup due to fast rotation,” Agarwal says, with the resulting fragments possibly being pushed further apart by “sublimation torques.” Binary asteroid systems are relatively common, but 288P stands out through the wide berth between the two component bodies, their near-equal size and mass, high eccentricity, and comet-like features, making 288P unique among known asteroid binaries in the Solar System.

One of the questions scientists are trying to answer when looking at main-belt bodies (comets as well as asteroids) is whether or not they shuttled water from space to young Earth, helping create the oceans of today. We don’t get to see a lot of them up close, so 288P stands out as an extremely important system for future studies. Its uniqueness also poses some problems, however. It’s so starkly different from anything else we’ve seen that we don’t have anything to meaningfully compare it with — so we don’t know if its properties are a fluke or quite common.

“We need more theoretical and observational work, as well as more objects similar to 288P, to find an answer to this question,” concludes Agarwal.

Since snapping 288P involved quite a bit of luck, it may be quite a while before we spot these objects, though.

The paper “A binary main belt comet” has been published on ESA’s hubblesite, here.


Landslide spotted on comet for the first time using Rosetta’s images

A 100-meter cliff on Comet 67P was caught by the Rosetta’s spacecraft’s cameras as it dramatically collapsed. It’s the first time a landslide on a comet was documented.


This image taken on July, 2015, shows a white outburst emanating from comet 67P. The bright flash is radiating ice exposed by a cliff which collapsed. Credit: ESA/Rosetta/NavCam

A while ago, Maurizio Pajola, an astronomer at the Nasa Ames Research Center, California, was up late at night casually browsing images taken by the famous Rosetta spacecraft when he came across something strange. He saw a bright patch emanating out of the comet’s dim surface in a photo taken by ESA’s spacecraft in December, 2015. So Pajola went through the catalog of images that focus on the region in question, a cliff called Aswan. He eventually came across an image snapped in on July 10, 2015 were a large plume of dust was showing. A snapshot taken just five days later clearly showed the cliff had collapsed, linking the bright outburst to the landslide. In the wake of the landslide, a giant 70 metres-long by one metre-wide fracture was carved.

When the cliff collapsed, it exposed a patch of pristine ice which radiated strongly which explains the bright features at the top of Comet 67P that Pajola had initially witnessed.

A 70 metre-long, 1 metre-wide fracture was created in the wake of the cliff's collapse. Take a moment to appreciate how sharp these images are -- taken by a spacecraft orbiting a freaking comet millions of miles away from Earth. Credit: ESA.

A 70 metre-long, 1 metre-wide fracture was created in the wake of the cliff’s collapse. Take a moment to appreciate how sharp these images are — taken by a spacecraft orbiting a freaking comet millions of miles away from Earth. Credit: ESA.

Previously, scientists had thought such outbursts, seen before in other comets, were the result of pressurized gas that blasted through the comet’s warm interior. Now, astronomers need to rethink the mechanics of such events often observed in comets which come too close to the sun.

In the same study published in Nature Astronomy, Pajola and colleagues simulated the conditions on the surface of the comet at the time when the cliff collapsed. Around July 2015, temperatures sharply rose from an ungodly -143 degrees Celsius to scorching 46 degrees celsius in only 20 minutes as the comet dropped from the shadow and came face to face with the sun’s rays. Every 12 hours, the cliff was directly exposed to the sun for one and a half hours. This tug of war of expansion/contraction triggered by the temperature gradients eventually cracked the cliff causing it to collapse.

“This is the most compelling evidence that we have that the observed outburst was directly linked to the collapse of the cliff,” said Maurizio Pajola, an astronomer at the Nasa Ames Research Center, California, and the study’s lead author.

The findings yet again confirm that comets aren’t just benign chunks of dust and ice — they’re very much geologically active, Pajola says. Cliffs collapse, boulders roll, dust migrates all the time. There are even sinkholes. A lot of things are happening.

After two years spent orbiting around comet 67P, which culminated with landing a robotic probe on the comet’s surface, the 12-year-long mission came to an end last year, in September. Data gathered by the probe, such as the high-resolution images analyzed by Pajola and colleagues is still keeping scientists busy, however. Science will likely benefit from Rosetta for another decade underscoring its importance.

Comet collision caused rapid carbon rise in ancient times

Some 55.6 million years ago, at the end of a period called the Paleocene, Earth’s temperature suddenly rose fueled by a dramatic release of carbon in the atmosphere. The period is often used in climate studies as the closest analog to today’s reality of man-made climate change. But there might be a key difference between that situation and today’s situation – a comet.

Microtektites as first seen in a sediment sample from the onset of the Paeocene-Eocene Thermal Maximum. Credit: Rensselaer Polytechnic Institute

PETM vs man-made global warming

That period was called the Paleocene–Eocene Thermal Maximum (PETM). During the PETM, temperatures rose by as much as 8 °C (over 14F) and geological evidence suggests that the effect on Earth’s life was tremendous. Massive extinction events ensued both on land and in the seas, accompanied by massive mammal migration to northern, friendlier climates. Polar ice melted completely and sea levels rose dramatically all around the globe, with effects being felt for at least 200,000 years. However, the causes and evolution of this phenomenon remain simply perplexing – basically, we really don’t know why this happened.

But even with all these massive changes, many researchers believe today’s man-made changes surpass anything we’ve seen during PETM. As a result, the consequences will also be more dramatic. Just earlier this year, a study led by Richard Zeebe of the University of Hawaii found that humans are now pumping carbon into the atmosphere 10 times faster than whatever natural forces drove the PETM.

Comet and carbon

A team of researchers may have found an unlikely explanation for PETM. While they don’t claim this directly, they provide some indication that a comet might be the cause for this dramatic change.

“This could very well be the ground zero” of the PETM, said coauthor Dennis Kent, a researcher at Columbia University’s Lamont-Doherty Earth Observatory and Rutgers University. “It got warm in a hurry. This suggests where it came from.”

The study analyzed glassy silica spherules called microtektites. Microtektites are bodies composed of black, green, brown or gray natural glass formed from terrestrial debris ejected during meteorite or comet impacts. When the impact takes place, matter is vaporized and splashed all over the place, creating these highly distinctive particles. The study’s lead author, geochemist Morgan Schaller of Rensselaer Polytechnic Institute, and his student Megan Fung spotted the sand-grain-size spherules at the base of a layer of fine clay believed to mark the start of the PETM. They haven’t yet established any causation, but if it’s a coincidence… then it’s one heck of a coincidence.

“It’s got to be more than coincidental that there’s an impact right at the same time,” said Schaller. “If the impact was related, it suggests the carbon release was fast.”

However, they still haven’t found a crater – and without a crater, claiming such an impact is hard to prove. The microtektites they found were thin and widely spread, which would either suggest that the impact was close but small, or larger but much farther away. The latter seems more likely.

“It could have been next door, or it could have been on the other side of the planet,” said Schaller.

Charles Langmuir, a prominent paleoclimate researcher at Harvard University who was not involved in the study, said the evidence of an impact at or near the PETM boundary was “very strong,” but he raises another question: how did the impact actually release all that carbon. There’s also a possibility of the particles coming from another layer and getting mixed with the PETM layer. All in all, it’s an intriguing hypothesis, but we still need a bit more to back it up.