New Study of Antares Creates the Best Map Ever of a Distant Star

Using ESO’s Very Large Telescope Interferometer astronomers have constructed this remarkable image of the red supergiant star Antares. This is the most detailed image ever of this object, or any other star apart from the Sun.

When stars exhaust their supply of hydrogen fuel, they exit the main sequence phase of their evolution and enter into what is known as the Red Giant Branch (RGB) phase. This is characterized by the stars expanding significantly and becoming tens of thousands of times larger than our Sun. They also become dimmer and cooler, which lends them a reddish-orange appearance (hence the name).

Recently, a team of astronomers used the ESO’s Very Large Telescope Interferometer (VLTI) to map one such star, the red supergiant Antares. In so doing, they were able to create the most detailed map of a star other than our Sun. The images they took also revealed some unexpected things about this supergiant star, all of which could help astronomers to better understand the dynamics and evolution of red giant stars.

The study which details their work, titled “Vigorous Atmospheric Motions in the Red Supergiant Supernova Progenitor Antares“, recently appeared in the journal Nature. As indicated in the study, the team – which was led by Keiichi Ohnaka, an associate professor at the UCN Institute of Astronomy in Chile = relied on the VLTI at the ESO’s Paranal Observatory in Chile to map Antares’s surface and measure the motions of its surface material.

Artist’s impression of the red supergiant star Antares, located 550 ly away in the constellation of Scorpius. Credit: ESO/M. Kornmesser

The purpose of their study was to chart how stars that have entered their RGB phase begin to change. The VLTI is uniquely suited to this task, since it is capable of combining light from four different telescopes – the 8.2-metre Unit Telescopes, or the smaller Auxiliary Telescopes – to create one virtual telescope that has the resolution of a telescope lens measuring 200 meters across.

This allows the VLTI to resolve fine details far beyond what can be seen with a single telescope. As Prof. Ohnaka explained in a recent ESO press statement:

How stars like Antares lose mass so quickly in the final phase of their evolution has been a problem for over half a century. The VLTI is the only facility that can directly measure the gas motions in the extended atmosphere of Antares — a crucial step towards clarifying this problem. The next challenge is to identify what’s driving the turbulent motions.”

For their study, the team relied on three of the VLTI Auxiliary Telescopes and an instrument called the Astronomical Multi-BEam combineR (AMBER). This near-infrared spectro-interferometric instrument combines three telescopic beams coherently, allowing astronomers to measure the visibilities and closure phases of stars. Using these instruments, the team obtained images of Antares’ surface over a small range of infrared wavelengths.

From these, the team was able to calculate the difference between the speed of atmospheric gas at different locations on Antares’ surface, as well as its average speed over the entire surface. This resulted in a two-dimensional velocity map of Antares, which is the first such map created of another star other than the Sun. As noted, it is also the most-detailed map of any star beyond our Solar System to date.

The study also made some interesting discoveries of what takes place on Antares’ surface and in its atmosphere. For example, they found evidence for high-speed upwellings of gas that reached distances of up to 1.7 Solar radii into space – much farther than previously thought. This, they claimed, could not be explained by convection alone, the process whereby cold material moves downwards and hot material upwards in a circular pattern.

This process occurs on Earth in the atmosphere and with ocean currents, but it is also responsible for moving pockets of hotter and colder gas around within stars. The fact that convection cannot explain the behavior of Antares extended atmosphere would therefore suggests that some new and unidentified process common to red giant stars must be responsible.

These results therefor offer new opportunities for research into stellar evolution, which is made possible thanks to next-generation instruments like the VTLI. As Ohnaka concluded:

“In the future, this observing technique can be applied to different types of stars to study their surfaces and atmospheres in unprecedented detail. This has been limited to just the Sun up to now. Our work brings stellar astrophysics to a new dimension and opens an entirely new window to observe stars.”

Not only is this kind of research improving our understanding of stars beyond our Solar System, it lets us know what to expect when our Sun exits it main sequence phase and begins expanding to become a red giant. Though that day is billions of years away and we can’t be certain humanity will even be around by that time, knowing the mechanics of stellar evolution is important to our understanding of the Universe.
It pays to know that even after we are gone, we can predict what will still be here and for how long. Be sure to check out this 3D animation of Antares, courtesy of the ESO:

Further Reading: ESO, Nature

Witnessing the 2017 Total Solar Eclipse Across America Mesmerizes Millions: Photo/Video Gallery

Solar corona and prominences during the total solar eclipse across America on Monday, August 21, 2017, as seen from Santee, South Carolina and 4.8 miles from the centerline. Credit: Ken Kremer/kenkremer.com
Solar corona and prominences during the total solar eclipse across America on Monday, August 21, 2017, as seen from Santee, South Carolina and 4.8 miles from the centerline. Credit: Ken Kremer/kenkremer.com

SANTEE, SOUTH CAROLINA – Witnessing ‘Totality’ during Monday’s ‘Great American Solar Eclipse’ was a truly mesmerizing experience far beyond anything I imagined and something I will never forget -That’s a sentiment shared by millions upon millions of fellow gushing spectators.

I was stationed in Santee, South Carolina, near Lake Marion and close to the centerline of Totality, along with space journalist friend and colleague Jeff Seibert. And we could not have asked for clearer skies to enjoy this awesome natural event made possible by a uniquely rare confluence of miraculous celestial mechanics.

Check out our expanding gallery of personal photos and videos as well as many more gathered from friends and colleagues herein.

Totality was mesmerizing! Although I fully hoped to see a science spectacle (weather permitting) – I wasn’t really prepared for the majesty of the ‘coronal fire’ of Totality on display in the sky that started with what seemed like a startling electric flash – – The sun was alive far beyond anything I imagined beforehand. An out of body experience truly beyond my wildest dreams.

And we really lucked out with the weather – – as the odds of good weather are apparently better near Lake Marion, local residents told me. Just 15 miles south in Saint George, SC where I held a well attended eclipse outreach event at my hotel the night before, it was sadly socked in.

Solar corona bursts out during the total solar eclipse across America on Monday, August 21, 2017, as seen from Santee, South Carolina and 4.8 miles from the centerline. Credit: Ken Kremer/kenkremer.com

Despite a less than promising weather forecast, the threatening Carolina storm clouds obscuring our sun as we awoke and got our camera gear together Monday morning, fortunately scooted away.

Just in the nick of time the rainy gray breakfast clouds miraculously parted as eclipse time approached and almost completely disappeared by lunchtime – fully an hour prior to the eclipses beginning from our viewing location in Santee; near beautiful Lake Marion, South Carolina, which intersects the heavily traveled I-95 North/South Interstate highway corridor.

Like tens of millions of others, I’ve seen several partial solar eclipses, but this was my first total solar eclipse and it did not disappoint!

And there is just no comparison between seeing a partial and a total solar eclipse – sort of like a family before and after having a baby.

Solar corona and multiple prominences visible during the total solar eclipse across America on Monday, August 21, 2017, as seen from Santee, South Carolina and 4.8 miles from the centerline. Credit: Ken Kremer/kenkremer.com

A few hundred excited people from across the East Coast including some families with kids had coincidentally gathered at our Santee location by the Water Park.

At Santee, SC, we enjoyed unobstructed totality for all 2 minutes, 34 seconds – very close to the longest possible duration of 2 min 43 seconds experienced by folks congregated in Carbondale, Illinois.

Overall our eclipse experience began at 1:14:55 p.m. EDT and concluded at 4:08:01 EDT – nearly three hours.

Totality started at 2:43:42 p.m. EDT and concluded at 2:46:16 p.m. EDT.

View shows partial solar eclipse as the moon begins obscuring the sun on the way to totality during the 2017 total solar eclipse on August 21, as seen from Santee, South Carolina and close to the centerline. Credit: Ken Kremer/kenkremer.com

At lunchtime it was a boiling hot, skin stinging 95+ degrees F. But barely half an hour into the eclipse and with the sun perhaps only a third covered the area noticeably cooled and darkened and the sunburn was gone.

As the eclipse deepened, the sky really darkened to the point we almost needed a flashlight and it was downright comfortable temperature wise.

I’m over the Moon so to speak and still replaying the totality event in my mind from start to finish.

You can follow along by watching this thrilling solar eclipse video produced by Jeff Seibert, and listen to the cheering crowd to get a sense of our Carolina Totality adventure:

Video Caption: Total Solar eclipse from Santee, SC on August 21, 2017. We were 4.8 miles South of the Umbra center line, and had clear weather until just before last contact. Credit: Jeff Seibert

At Santee we were 87% into the umbra with a 70 mile wide (115 km) lunar shadow path width, at 136 feet elevation above sea level.

There is just nothing like ‘Totality’ in my experience as a research scientist and journalist – working with and seeing cool science and space hardware up close.

Totality is a natural wonder of the Universe and it was an electrifying event.

At the moment that totality commenced, day turned almost instantly to night as though someone threw a light switch.

I distinctly heard crackling sounds burst through the air, akin to a thunderbolt clap at that very moment – heralding our sudden jolt to totality.

Cheers broke out. Everyone and myself were so totally in awe of totality. And the sun’s brilliant while corona suddenly became visible, alive and in motion as the solar surface was completely blocked, hidden behind our moon. So I just stared at the stunning beauty, barely able to function as a photographer.

The planet Venus quickly and suddenly and incredibly popped out brilliantly from the darkness of the daytime sky. Some stars were also visible.

You absolutely must experience this incomparable wonder of nature with you own eyeballs.

Focus on the fleeting moment.

Because in a flash of just 2.5 minutes #Eclipse2017 was gone & done!

The all natural light switch had been turned back on by mother nature herself.

If only a replay or restart were possible – someone in the crowd yelled in glee. And we all thought the same way.

Totality, like rockets and science can be addictive in a very positive way.

Furthermore, we also saw the famed partial solar crescents reflecting through trees onto the ground during the partial eclipse phases.

A sliver of the sun reappears after totality concludes during the 2017 total solar eclipse on August 21, as seen from Santee, South Carolina and close to the centerline. Credit: Ken Kremer/kenkremer.com

We very luckily enjoyed virtually perfect weather and clear blue skies for the entirely of the eclipse – from first contact, through totality and the last limb of contact of Earth’s moon covering the sun.

Only a few scattered cloud patches dotted overhead at the start and rapidly exited.

And very happily we were not alone.

The Aug. 21 ‘Total Solar ‘Eclipse Across America’ was enjoyed by tens of millions more lucky spectators, including many friends lining the solar eclipses narrow path of Totality from coast to coast.

The 70-mile-wide (115 km) swath of the Moons shadow raced across America from Oregon to South Carolina in a thrilling event that became sort of a communal experience with all the explanatory news coverage foreshadowing what was to come.

Everyone in North America was able to witness at least a partial solar eclipse, weather permitting- and many did either on there own or at special solar eclipse events organized at towns and cities at museums, parks and open spaces across the country.

12 million people live directly in the path of 2017 solar eclipse totality as it passed through 14 states.

It was the first total solar eclipse visible from the United States since Feb. 26, 1979. And it was the first such coast to coast eclipse crossing the entire continental United States in 99 years since June 8, 1918 during World War 1.

The umbra (or dark inner shadow) of the Moon moved west to east at 3000 MPH in Oregon and 1500 MPH by the time it reached our location in South Carolina.

The 2017 solar eclipse began on the west coast with the lunar shadow entering the US near Lincoln City, Oregon at 9:05 PDT, with totality beginning at 10:15 PDT, according to a NASA description.

Totality ended along the US East Coast in the coastal city of Charleston, South Carolina at 2:48 p.m. EDT. The last remnants of lunar shadow departed at 4:09 p.m. EDT. Charleston is about an hour or so east of my viewing location in Santee and folks there enjoyed stunning views too.

For as long as I live the 2017 Solar Eclipse Totality will be burned into my mind!

Partial solar eclipse as seen from Port Canaveral, Florida where a maximum of about 86% of the sun was covered during the 2017 total solar eclipse on August 21, 2017. Credit: Julia Bergeron

“I’m pretty sure it was not nearly as epic as the total eclipse. It was fun to watch with teenagers though. I think what was unique to me was that I was capturing the equivalent of a crescent sun. Did it get dark here, of course not, but there were a few minutes where the Space Coast went a bit dim. The most fun was looking for the shadows,” writes Julia Bergeron from Port Canaveral, FL.

Partial solar eclipse as seen from Port Canaveral, Florida where a maximum of about 86% of the sun was covered during the 2017 total solar eclipse on August 21, 2017. Credit: Julia Bergeron
The 2017 Total solar eclipse as seen from a cell phone through eclipse glasses and reached about 86% of totality in this view from Titusville, Florida on Aug. 21, 2017. Credit: Ashley Carrillo
The 2017 Total solar eclipse as seen from a cell phone through eclipse glasses and reached about 86% of totality in this view from Titusville, Florida on Aug. 21, 2017. Credit: Ashley Carrillo

Watch for Ken’s continuing onsite Minotaur IV ORS-5, TDRS-M, CRS-12 and NASA and space mission reports direct from the Kennedy Space Center and Cape Canaveral Air Force Station, Florida.

Stay tuned here for Ken’s continuing Earth and Planetary science and human spaceflight news.

Ken Kremer

The 2017 Total solar eclipse as seen through eclipse glasses reached about 86% of totality in this view from Melbourne, Florida on Aug. 21, 2017. Credit: Julian Leek

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Learn more about the 2017 Total Solar Eclipse, upcoming Minotaur IV ORS-5 military launch on Aug. 25, recent ULA Atlas TDRS-M NASA comsat on Aug. 18, 2017 , SpaceX Dragon CRS-12 resupply launch to ISS on Aug. 14, NASA missions and more at Ken’s upcoming outreach events at Kennedy Space Center Quality Inn, Titusville, FL:

Aug 24-26: “2017 Total Solar Eclipse Minotaur IV ORS-5, TDRS-M NASA comsat, SpaceX CRS-12 resupply launches to the ISS, Intelsat35e, BulgariaSat 1 and NRO Spysat, SLS, Orion, Commercial crew capsules from Boeing and SpaceX , Heroes and Legends at KSCVC, ULA Atlas/John Glenn Cygnus launch to ISS, SBIRS GEO 3 launch, GOES-R weather satellite launch, OSIRIS-Rex, Juno at Jupiter, InSight Mars lander, SpaceX and Orbital ATK cargo missions to the ISS, ULA Delta 4 Heavy spy satellite, Curiosity and Opportunity explore Mars, Pluto and more,” Kennedy Space Center Quality Inn, Titusville, FL, evenings

Solar crescents projected on the ground after sunlight funnels through trees during the partial eclipse phases on Aug. 21, 2017. Credit: Julian Leek
Solar crescents projected onto the top of a picnic cooler and pine needles on the ground after sunlight funnels through trees during the partial eclipse phases on August 21 in Santee, SC. Credit: Ken Kremer/kenkremer.com
2017 Total Solar Eclipse as seen from Red Bank, SC. Credit: John Gould
Solar crescents projected on the ground after sunlight funnels through trees during the partial eclipse phases from Red Bank, SC on Aug. 21, 2017. Credit: John Gould

“Astonished at the vivacity and brightness of the corona, and the contrast with the infinitely dark moon. Through binos it almost had me in tears,” writes John Gould from Red Bank, SC.

2017 Total Solar Eclipse and Bailey’s Beads as seen from Santee State Park, SC. Credit: Patrick Hendrickson/HighCamera Photographic Service
Total Solar Eclipse of 2017 as seen from Tennessee. Credit: Dawn Leek Taylor
Total Solar Eclipse of 2017 as seen from Tennessee. Credit: Dawn Leek Taylor

Mars Express Captures Mars’ Moving Bow Shock

Artist's impression of the moving Martian bow shock. Credit: ESA/ATG medialab

Every planet in our Solar System interacts with the stream of energetic particles coming from our Sun. Often referred to as “solar wind”, these particles consist mainly of electrons, protons and alpha particles that are constantly making their way towards interstellar space. Where this stream comes into contact with a planet’s magnetosphere or atmosphere, it forms a region around them known as a “bow shock”.

These regions form in front of the planet, slowing and diverting solar wind as it moves past – much like how water is diverted around a boat. In the case of Mars, it is the planet’s ionosphere that provides the conductive environment necessary for a bow shock to form. And according to a new study by a team of European scientists, Mars’ bow shock shifts as a result of changes in the planet’s atmosphere.

The study, titled “Annual Variations in the Martian Bow Shock Location as Observed by the Mars Express Mission“, appeared in the Journal of Geophysical Letters: Space Physics. Using data from the Mars Express orbiter, the science team sought to investigate how and why the bow shock’s location varies during the course of several Martian years, and what factors are chiefly be responsible.

Diagram of Mars’ orbit and changes to its bow shock between perihelion and aphelion. Credit: ESA/ATG medialab

For many decades, astronomers have been aware that bow shocks form upstream of a planet, where interaction between solar wind and the planet causes energetic particles to slow down and gradually be diverted. Where the solar wind meets the planet’s magnetosphere or atmosphere, a sharp boundary line is formed, which them extends around the planet in a widening arc.

This is where the term bow shock comes from, owing to its distinctive shape. In the case of Mars, which does not have a global magnetic field and a rather thin atmosphere to boot (less than 1% of Earth’s atmospheric pressure at sea level), it is the electrically-charged region of the upper atmosphere (the ionosphere) that is responsible for creating the bow shock around the planet.

At the same time, Mars relatively small size, mass and gravity allows for the formation of an extended atmosphere (i.e. an exosphere). In this portion of Mars’ atmosphere, gaseous atoms and molecules escape into space and interact directly with solar wind. Over the years, this extended atmosphere and Mars’ bow shock have been observed by multiple orbiter missions, which have detected variations in the latter’s boundary.

This is believed to be caused by multiple factors, not the least of which is distance. Because Mars has an relatively eccentric orbit (0.0934 compared to Earth’s 0.0167), its distance from the Sun varies quite a bit – going from 206.7 million km (128.437 million mi; 1.3814 AU) at perihelion to 249.2 million km (154.8457 million mi; 1.666 AU) at aphelion.

Illustration showing how Mars and Earth interact with solar wind. Credit: NASA

When the planet is closer, the dynamic pressure of the solar wind against its atmosphere increases. However, this change in distance also coincides with increases in the amount of incoming extreme ultraviolet (EUV) solar radiation. As a result, the rate at which ions and electrons (aka. plasma) are produced in the upper atmosphere increases, causing increased thermal pressure that counteracts the incoming solar wind.

Newly-created ions within the extended atmosphere are also picked up and accelerated by the electromagnetic fields being carried by the solar wind. This has the effect of slowing it down and causing Mars’ bowshock to shift its position. All of this has been known to happen over the course of a single Martian year – which is equivalent to 686.971 Earth days or 668.5991 Martian days (sols).

However, how it behaves over longer periods of time is a question that was previously unanswered. As such, the team of European scientists consulted data obtained by the Mars Express mission over a five year period. This data was taken by the Analyser of Space Plasma and EneRgetic Atoms (ASPERA-3) Electron Spectrometer (ELS), which the team used to examine a total of 11,861 bow shock crossings.

What they found was that, on average, the bow shock is closer to Mars when it is near aphelion (8102 km), and further away at perihelion (8984 km). This works out to a variation of about 11% during the Martian year, which is pretty consistent with its eccentricity. However, the team wanted to see which (if any) of the previously-studied mechanisms was chiefly responsible for this change.

The moving Martian bow shock. Credit: ESA/ATG medialab

Towards this end, the team considered variations in solar wind density, the strength of the interplanetary magnetic field, and solar irradiation as primary causes – are all of which decline as the planet gets farther away from the Sun. However, what they found was that the bow shock’s location appeared more sensitive to variations in the Sun’s output of extreme UV radiation rather than to variations in solar wind itself.

The variations in bow shock distance also appeared to be related to the amount of dust in the Martian atmosphere. This increases as Mars approaches perihelion, causing the atmosphere to absorb more solar radiation and heat up. Much like how increased levels of EUV leads to an increased amount of plasma in the ionosphere and exosphere, increased amounts of dust appear to act as a buffer against solar wind.

As Benjamin Hall, a researcher at Lancaster University in the UK and the lead author of the paper, said in an ESA press release:

“Dust storms have been previously shown to interact with the upper atmosphere and ionosphere of Mars, so there may be an indirect coupling between the dust storms and bow shock location… However, we do not draw any further conclusions on how the dust storms could directly impact the location of the Martian bow shock and leave such an investigation to a future study.”

In the end, Hall and his team could not single out any one factor when addressing why Mars’ bow shock shifts over longer periods of time. “It seems likely that no single mechanism can explain our observations, but rather a combined effect of all of them,” he said. “At this point none of them can be excluded.”

Looking ahead, Hall and his colleagues hope that future missions will help shed additional light on the mechanisms behind Mars shifting bowshock. As Hall indicated, this will likely involve “”joint investigations by ESA’s Mars Express and Trace Gas Orbiter, and NASA’s MAVEN mission. Early data from MAVEN seems to confirm the trends that we discovered.”

While this is not the first analysis that sought to understand how Mars’ atmosphere interacts with solar wind, this particular analysis was based on data obtained over a much longer period of time than any previously study. In the end, the multiple missions that are currently studying Mars are revealing much about the atmospheric dynamics of this planet. A planet which, unlike Earth, has a very weak magnetic field.

What we learn in the process will go a long way towards ensuring that future exploration missions to Mars and other planets that have weak magnetic fields (like Venus and Mercury) are safe and effective. It might even assist us with the creation of permanent bases on these worlds someday!

Further Reading: ESA, Journal of Geophysical Research: Space Physics

Elon Musk Reveals New SpaceX Spacesuit

Elon Musk shared a photo on Instagram of SpaceX's spacesuit design. Credit: Elon Musk.

SpaceX CEO and founder Elon Musk made public the first official photo of the commercial space company’s spacesuit design with a post on Instagram today. He indicated he’ll have more details soon and said this first ‘reveal’ isn’t just a prototype design; it’s a real, working spacesuit.

“Worth noting that this actually works (not a mockup)” Musk said. “Already tested to double vacuum pressure.”

The person inside the suit – in what looks to be a computer generated photo – looks much like Musk himself, although the face is rather hard to make out.

Following the design of many previous spacesuits, it comes in white. Musk said in designing the suit, it was “incredibly hard to balance esthetics and function. Easy to do either separately.”

There has been some discussion on social media about the orientation of the flag, as it appears to many to be “backward.” However, this follows US military custom of flags on uniforms, positioned on the right shoulder in this same orientation, with stars facing forward. This gives the effect of the flag “flying in the breeze” as the person in the uniform/spacesuit moves forward.

These are the spacesuits that will be worn by the astronauts who make the first flights on the Dragon Capsule to the International Space Station as part of the commercial crew program. The target for the first humans aboard Dragon is next year, mid-2018.

If you are looking for a spacesuit that has a little more pop of color — as well as a heart-felt mission — NASA also held a special news conference from the International Space Station today revealing a colorful new spacesuit created by children around the world who are suffering from cancer.

The Space Suit Art Project is a collaboration between NASA, spacesuit maker ILC Dover and children in hospitals around the world. This suit, called Unity, is the third in a series of suits. The suits are made of colorful patches made by young cancer patients, giving the kids an opportunity to be part of a lasting and out-of-this-world project.

Astronaut Jack Fischer donned the special (non-functioning) spacesuit and said it was tricky to get into, just like a real spacesuit. But this suit, Fischer said, “gives you the honor to represent the bravest kids in the world, who put it together.” Fischer’s daughter Bethany, is a cancer survivor.

Hallelujah, It’s Raining Diamonds! Just like the Insides of Uranus and Neptune.

An experiment conducted by an international team of scientists recreated the "diamond rain" believed to exist in the interiors of ice giants like Uranus and Neptune. Credit: Greg Stewart/SLAC National Accelerator Laboratory

For more than three decades, the internal structure and evolution of Uranus and Neptune has been a subject of debate among scientists. Given their distance from Earth and the fact that only a few robotic spacecraft have studied them directly, what goes on inside these ice giants is still something of a mystery. In lieu of direct evidence, scientists have relied on models and experiments to replicate the conditions in their interiors.

For instance, it has been theorized that within Uranus and Neptune, the extreme pressure conditions squeeze hydrogen and carbon into diamonds, which then sink down into the interior. Thanks to an experiment conducted by an international team of scientists, this “diamond rain” was recreated under laboratory conditions for the first time, giving us the first glimpse into what things could be like inside ice giants.

The study which details this experiment, titled “Formation of Diamonds in Laser-Compressed Hydrocarbons at Planetary Interior Conditions“, recently appeared in the journal Nature Astronomy. Led by Dr. Dominik Kraus, a physicist from the Helmholtz-Zentrum Dresden-Rossendorf Institute of Radiation Physics, the team included members from the SLAC National Accelerator Laboratory, the Lawrence Livermore National Laboratory and UC Berkeley.

Uranus and Neptune, the Solar System’s ice giant planets. Credit: Wikipedia Commons

For decades, scientists have held that the interiors of planets like Uranus and Neptune consist of solid cores surrounded by a dense concentrations of “ices”. In this case, ice refers to hydrogen molecules connected to lighter elements (i.e. as carbon, oxygen and/or nitrogen) to create compounds like water and ammonia. Under extreme pressure conditions, these compounds become semi-solid, forming “slush”.

And at roughly 10,000 kilometers (6214 mi) beneath the surface of these planets, the compression of hydrocarbons is thought to create diamonds. To recreate these conditions, the international team subjected a sample of polystyrene plastic to two shock waves using an intense optical laser at the Matter in Extreme Conditions (MEC) instrument, which they then paired with x-ray pulses from the SLAC’s Linac Coherent Light Source (LCLS).

As Dr. Kraus, the head of a Helmholtz Young Investigator Group at HZDR, explained in an HZDR press release:

“So far, no one has been able to directly observe these sparkling showers in an experimental setting. In our experiment, we exposed a special kind of plastic – polystyrene, which also consists of a mix of carbon and hydrogen – to conditions similar to those inside Neptune or Uranus.”

The plastic in this experiment simulated compounds formed from methane, a molecule that consists of one carbon atom bound to four hydrogen atoms. It is the presence of this compound that gives both Uranus and Neptune their distinct blue coloring. In the intermediate layers of these planets, it also forms hydrocarbon chains that are compressed into diamonds that could be millions of karats in weight.

The MEC hutch of SLAC’s LCLS Far Experiement Hall. Credit: SLAC National Accelerator Laboratory

The optical laser the team employed created two shock waves which accurately simulated the temperature and pressure conditions at the intermediate layers of Uranus and Neptune. The first shock was smaller and slower, and was then overtaken by the stronger second shock. When they overlapped, the pressure peaked and tiny diamonds began to form. At this point, the team probed the reactions with x-ray pulses from the LCLS.

This technique, known as x-ray diffraction, allowed the team to see the small diamonds form in real-time, which was necessary since a reaction of this kind can only last for fractions of a second. As Siegfried Glenzer, a professor of photon science at SLAC and a co-author of the paper, explained:

“For this experiment, we had LCLS, the brightest X-ray source in the world. You need these intense, fast pulses of X-rays to unambiguously see the structure of these diamonds, because they are only formed in the laboratory for such a very short time.”

In the end, the research team found that nearly every carbon atom in the original plastic sample was incorporated into small diamond structures. While they measured just a few nanometers in diameter, the team predicts that on Uranus and Neptune, the diamonds would be much larger. Over time, they speculate that these could sink into the planets’ atmospheres and form a layer of diamond around the core.

The interior structure of Neptune. Credit: Moscow Institute of Physics and Technology

In previous studies, attempts to recreate the conditions in Uranus and Neptune’s interior met with limited success. While they showed results that indicated the formation of graphite and diamonds, the teams conducting them could not capture the measurements in real-time. As noted, the extreme temperatures and pressures that exist within gas/ice giants can only be simulated in a laboratory for very short periods of time.

However, thanks to LCLS – which creates X-ray pulses a billion times brighter than previous instruments and fires them at a rate of about 120 pulses per second (each one lasting just quadrillionths of a second) – the science team was able to directly measure the chemical reaction for the first time. In the end, these results are of particular significance to planetary scientists who specialize in the study of how planets form and evolve.

As Kraus explained, it could cause to rethink the relationship between a planet’s mass and its radius, and lead to new models of planet classification:

“With planets, the relationship between mass and radius can tell scientists quite a bit about the chemistry. And the chemistry that happens in the interior can provide additional information about some of the defining features of the planet… We can’t go inside the planets and look at them, so these laboratory experiments complement satellite and telescope observations.”

This experiment also opens new possibilities for matter compression and the creation of synthetic materials. Nanodiamonds currently have many commercial applications – i.e. medicine, electronics, scientific equipment, etc, – and creating them with lasers would be far more cost-effective and safe than current methods (which involve explosives).

Fusion research, which also relies on creating extreme pressure and temperature conditions to generate abundant energy, could also benefit from this experiment. On top of that, the results of this study offer a tantalizing hint at what the cores of massive planets look like. In addition to being composed of silicate rock and metals, ice giants may also have a diamond layer at their core-mantle boundary.

Assuming we can create probes of sufficiently strong super-materials someday, wouldn’t that be worth looking into?

Further Reading: SLAC, HZDR, Nature Astronomy

 

Study of Moon Rocks Suggest Interior of the Moon is Really Dry

A Full Moon, as imaged by NASA's Lunar Reconnaissance Orbiter. Credit: NASA Goddard's Scientific Visualization Studio

Long before the Apollo missions reached the Moon, Earth’s only satellites has been the focal point of intense interest and research. But thanks to the samples of lunar rock that were returned to Earth by the Apollo astronauts, scientists have been able to conduct numerous studies to learn more about the Moon’s formation and history. A key research goal has been determining how much volatile elements the Moon possesses.

Intrinsic to this is determining how much water the Moon possesses, and whether it has a “wet” interior. If the Moon does have abundant sources of water, it will make establishing outposts there someday much more feasible. However, according to a new study by an international team of researchers, the interior of the Moon is likely very dry, which they concluded after studying a series of “rusty” lunar rock samples collected by the Apollo 16 mission.

The study, titled “Late-Stage Magmatic Outgassing from a Volatile-Depleted Moon“, appeared recently in the Proceedings of the National Academy of Sciences. Led by James M. D. Day of the Scripps Institution of Oceanography at the University of California, San Diego, the team’s research was funded by the NASA Emerging Worlds program – which finances research into the Solar System’s formation and early evolution.

Collection site of 66095 (bottom left) and the “Rusty Rock” lunar rock sample obtained there (center). Credit: NASA

Determining how rich the Moon is in terms of volatile elements and compounds – such as zinc, potassium, chlorine, and water – is important because it provides insight into how the Moon and Earth formed and evolved. The most-widely accepted theory is that Moon is the result of “catastrophic formation”, where a Mars-sized object (named Theia) collided with Earth about 4.5 billion years ago.

The debris kicked up by this impact eventually coalesced to form the Moon, which then moved away from Earth to assume its current orbit. In accordance with this theory, the Moon’s surface would have been an ocean of magma during its early history. As a result, volatile elements and compounds within the Moon’s mantle would have been depleted, much in the same way that the Earth’s upper mantle is depleted of these elements.

As Dr. Day explained in a Scripps Institution press statement:

“It’s been a big question whether the moon is wet or dry. It might seem like a trivial thing, but this is actually quite important. If the moon is dry – like we’ve thought for about the last 45 years, since the Apollo missions – it would be consistent with the formation of the Moon in some sort of cataclysmic impact event that formed it.”

Cross-polarized light image of a portion of the interior of the lunar ‘Rusty Rock’. Credit: NASA

For the sake of their study, the team examined a lunar rock named “Rusty Rock 66095” to determine the volatile content of the Moon’s interior. These rocks have mystified scientists since they were first brought back by the Apollo 16 mission in 1972. Water is an essential ingredient to rust, which led scientists to conclude that the Moon must have an indigenous source of water – something which seemed unlikely, given the Moon’s extremely tenuous atmosphere.

Using a new chemical analysis, Day and his colleagues determined the levels of istopically light zinc (Zn66) and heavy chlorine (Cl37), as well as the levels of heavy metals (uranium and lead) in the rock. Zinc was the key element here, since it is a volatile element that would have behaved somewhat like water under the extremely hot conditions that were present during the Moon’s formation.

Ultimately, the supply of volatiles and heavy metals in the sample support the theory that volatile enrichment of the lunar surface occurred as a result of vapor condensation. In other words, when the Moon’s surface was still an ocean of hot magma, its volatiles evaporated and escaped from the interior. Some of these then condensed and were deposited back on the surface as it cooled and solidified.

This would explain the volatile-rich nature of some rocks on the lunar surface, as well as the levels of light zinc in both the Rusty Rock samples and the previously-studied volcanic glass beads. Basically, both were enriched by water and other volatiles thanks to extreme outgassing from the Moon’s interior. However, these same conditions meant that most of the water in the Moon’s mantle would have evaporated and been lost to space.

Near-infrared image of the Moon’s surface by NASA’s Moon Mineralogy Mapper on the Indian Space Research Organization’s Chandrayaan-1 mission
Image credit: ISRO/NASA/JPL-Caltech/Brown Univ./USGS

This represents something of a paradox, in that it shows how rocks that contain water were formed in a very dry, interior part of the Moon. However, as Day indicated, it offers a sound explanation for an enduring lunar mystery:

“I think the Rusty Rock was seen for a long time as kind of this weird curiosity, but in reality, it’s telling us something very important about the interior of the moon. These rocks are the gifts that keep on giving because every time you use a new technique, these old rocks that were collected by Buzz Aldrin, Neil Armstrong, Charlie Duke, John Young, and the Apollo astronaut pioneers, you get these wonderful insights.”

These results contradict other studies that suggest the Moon’s interior is wet, one of which was recently conducted by researchers at Brown University. By combining data provided by Chandrayaan-1 and the Lunar Reconnaissance Orbiter (LRO) with new thermal profiles, the Brown research team concluded that lots of water exists within volcanic deposits on the Moon’s surface, which could also mean there are vast quantities of water in the Moon’s interior.

To these, Day emphasized that while these studies present evidence that water exists on the lunar surface, they have yet to offer a solid explanation for what mechanisms deposited it on the surface. Day and his colleague’s study also flies in the face of other recent studies, which claim that the Moon’s water came from an external source – either by comets which deposited it, or from Earth during the formation of the Earth-Moon system.

Other studies indicate that evidence from ancient volcanic deposits suggests that lunar magma contained substantial amounts of water, hinting at water in the interior. Credit: Olga Prilipko Huber

Those who believe that lunar water was deposited by comets cite the similarities between the ratios of hydrogen to deuterium (aka. “heavy hydrogen”) in both the Apollo lunar rock samples and known comets. Those who believe the Moon’s water came from Earth, on the other hand, point to the similarity between water isotopes on both the Moon and Earth.

In the end, future research is needed to confirm where all of the Moon’s water came from, and whether or not it exists within the Moon’s interior. Towards this end, one of Day’s PhD students – Carrie McIntosh – is conducting her own research into the lunar glass beads and the composition of the deposits. These and other research studies ought to settle the debate soon enough!

And not a moment too soon, considering that multiple space agencies hope to build a lunar outpost in the upcoming decades. If they hope to have a steady supply of water for creating hydrazene (rocket fuel) and growing plants, they’ll need to know if and where it can be found!

Further Reading: UC San Diego, PNAS

Tales From Totality: Standing in the Shadow of the Moon

A brilliant diamond ring punctuates totality. Image credit and copyright: Shahrin Ahmad.
A brilliant diamond ring punctuates totality. Image credit and copyright: Shahrin Ahmad.

They came, they saw, they battled clouds, traffic and strange charger adapters in a strange land. Yesterday, millions stood in awe as the shadow of the Moon rolled over the contiguous United States for the first time in a century. If you’re like us, your social media feed is now brimming with amazing images of yesterday’s total solar eclipse.

Already, we’ve seen some amazing reader images at Universe Today, with more to come. As a special look at a unique event, we’ve collected reader testimonies from every state along the path of totality of just what the eclipse was like.

Enjoy!

Oregon- Shahrin Ahmad (@Shahgazer)

We drove from Dalles at 3 AM. Nearing the observation spot, we got a flat tire! It was 5:30 AM, and no phone line! I sent a text to the land owner and somehow it reached him and we managed to be there by 6:30 AM. We observed from a secluded spot about 30 miles from Madras, with a 2 minutes and 2 seconds of totality. The sky was really clear during sunrise, but as totality approached we got some thin clouds hovering in the east. Luckily, it was thin enough to not spoil anything. The corona was incredibly beautiful with longer (streamers) jutting out at the 4 and 8 o’clock position. The first and second diamond ring were spectacular with the eye, probably with the help with the thin clouds. We calculated about 7 degree drop in temperature. The shadow was enormous, engulfing Mt Hood from the west and flew past above us towards and towards the Sun. Mesmerizing! 2 minutes simply was not enough, since this is probably my best view of a total solar eclipse so far!

The bright star Regulus, tangled up in the solar corona. Image credit and copyright: Shahrin Ahmad.

(Note: to our knowledge, no one witnessed the brief moments of totality as the umbra of the Moon brushed tiny corners of Montana and Iowa… if you’re reading this and did so, let us know!)

Idaho- Bruce McCurdy (@BruceMcCurdy)

How to describe such a magnificent spectacle in a “brief paragraph”? Our group from Edmonton observed totality under clear skies near Birch Creek, Idaho. After the Moon’s silhouette inexorably progressed & gradually swallowed up an impressive line of sunspots, the pace of dynamic events picked up dramatically in the minutes surrounding totality. The temperature dropped noticeably. Light faded & became “flat” while shadows became better defined & lost their fuzzy edges (penumbrae). The Moon’s onrushing shadow became visible on the mountains to our west, while rapidly-moving shadow bands squiggled on the ground around us. The sky took on an eerie indigo hue as the last vestiges of direct sunlight were obscured. A new & temporary centrepiece emerged in the sky: the black circle of the lunar night side highlighted by a spectacular corona, its far-flung pearly-white streamers contained within sharply defined edges. Around the black limb fiery coral pink prominences added intense colour highlights to the scene. Just beyond the corona gleamed Regulus, closer to the Sun than is possible for any other star of first magnitude or brighter, while off to one side Venus shone brilliantly, far higher in the sky than its customary window of dominance in normal twilight. All too soon the right edge of the lunar silhouette brightened, then blossomed in a brilliant diamond ring that continued to intensify for a couple of glorious seconds until filters again became a must. By now the mountains to our east were in darkness as the umbral shadow receded from our immediate location, leaving a number of our small party in tears from the intensity of the experience.

Wyoming- Kelly Kizer Whitt (@Astronomommy)

We woke up in the Tetons Monday morning to a sky streaked with clouds. But the hourly weather report showed clearing, so we headed to our spot before 7 AM. We were able to secure parking by our preferred observing location, the Mormon Barn with a view of the iconic Teton range in the background. Looking east, we saw the clouds slink away to the south until skies were blue and clear, despite lingering haze and smoke on the northern horizon from wildfires.

Crescent Suns along with the Tetons. image credit and copyright: Kelly Kizer Whitt.

Having been a science writer for two decades, I was well versed on total solar eclipses even though I’d never seen one first hand. But it didn’t unfold quite as I expected. The sky and air didn’t take on a twilight quality until the Sun was well over halfway obscured. Then when darkness fell, it came fast and the temperature dropped hard. We had on our eclipse glasses and were staring at the Sun, waiting to see bailey’s beads or the diamond ring. But first I glanced down and saw the slithering, wiggling lines of darkness and light known as the shadow bands. They have a truly creepy quality as they dance in the growing dark. Then we looked back up as the sliver of orange disappeared and the Sun winked out from our glasses. Pulling them off, my family let out cries of surprise when they saw the black hole where the Sun had been, surrounded by the long, wispy, intricate corona. The eclipsed Sun and corona took up a much larger space in the sky than I expected, but the photo I took (just like when photographing a full moon) does not give a true representation of what you can see with your eyes.

I only took three photos because I wanted to just enjoy the view. I almost forgot to look for the stars. We saw a plane, Venus, and Sirius. Our eyes never adjusted enough to spot Jupiter or the others and the rosy glow of a false twilight brightened all horizons in a 360-degree ring. So soon it was over. The bailey’s beads and diamond ring we missed as the total eclipse began, and appeared to us instead at the end. These phenomena were a bright and beautiful warning to get our eclipse glasses back on. The world returned to daylight fairly quickly, but the drop in temperature lingered a bit longer. Our memories will last a lifetime.

Nebraska- (@BigBadEd)

Having doubtful cloud forecasts for Scottsbluff & Carhenge,  we met on a foggy morning in Sidney, Nebraska with thoughts of changing plans to Wyoming for clear skies. As the forecast improved,  15 of us set off for Carhenge.  We arrived before 7 AM to plentiful parking & a few hundred people. Towards 9 AM the crowds started to swell, including aliens, welders and the governor of Nebraska. Joined by more people & dogs, I estimate around 3,000 people were at the site. Some clouds went by at mid-coverage, casting a spectacular crescent. Clouds cleared, and cheers rose as we went into totality,  such a beautiful sight some were moved to tears as the diamond ring emerged. A thoroughly wonderful experience shared with friends and spellbound crowd, definitely worth the trip from Florida.

Kansas- Michelle Tevis (@MichelleKTevis)

I saw it (the eclipse) from Weston, Missouri, just northwest of the Kansas-Missouri line. Clouds and rain obscured the sun for most of the eclipse, but the rain subsided during totality and allowed us to get outside for the quick move into darkness. Even though we couldn’t see the eclipse or corona, the atmosphere took on a different feel. There was a change in how things were colored — as if you were looking through darker and darker polarized glasses, and the silence took on a feeling, like a deep vibration.

Missouri- Jeudy Blanco (@Jeudyx)

Totality from Missouri. Image credit and copyright: Jeudy Blanco.

It was amazing. We changed plans last night, instead of going to St Joseph we drove to Columbia. I was really worried the first few minutes of the eclipse because it was cloudy, my PST couldn’t resolve the image of the Sun! But quickly the clouds dispersed. We were on a property from the family of my friend, around 25 people of all ages. When it was around 70% (partial) you could feel in the environment that something was going on. Everything got a lot more quiet and the temperature dropped. Everybody was trying to get pictures of the Sun with their phones on the PST. Then totality started, it was indescribable for me. I was seeing the Sun’s corona with my bare eyes. I was really nervous and anxious, actually. We could see Venus near the Sun. Everybody was super excited, I almost cried. The experience was amazing, a total success, the long trip was worth it.

Illinois- The Universe Today expedition to the Prairie State led by Publisher Fraser Cain also managed to catch a brief glimpse of totality through a gap in the clouds:

Kentucky- Mike Weasner (@Mweasner)

Earthshine (!) on the Moon, seen during totality. Image credit and copyright: Mike Weasner.

About 400 eclipse enthusiasts from around the world including me were part of a Sky and Telescope tour group. We were at Hopkinsville Community College located in Hopkinsville, Kentucky, where totality lasted 2 minutes and 40 seconds, which was too short. We arrived at the viewing site about 4.5 hours before First Contact. Traffic was surprisingly light. There were a few thin clouds but nothing significant. Anticipation was high. Many of us set up cameras and were ready well before First Contact. First Contact occurred with a clear sky, and the sky stayed mostly clear until about 30 minutes before Second Contact. Then a large cloud covered the Sun. Fortunately the cloud moved on within a couple of minutes and the sky was mostly clear through Fourth Contact. Totality was beautiful. Most people saw Venus, some saw Jupiter too, but no one seems to have seen any stars although it did get dark at the site. Many people in the group left soon after totality ended, but I and several others stayed to view and photograph the eclipse through Fourth Contact. 

Tennessee- (Terry Horne @CapH_1)

My wife and I viewed the event from Sheep Barn Ridge, which is a few miles from Kingston, TN. We began the planning in late 2015 when we realized the shadow path was adjacent to our property near my folks in TN. Our location delivered 2 minutes and 29 seconds of totality, with clear skies, a valley pasture view among new friends, goats, llama, ducks, chickens and a few hounds.

An amazing expample of the “Diamond Ring” effect. Image credit and copyright: Phyllis Horne @sahgma

We experienced every awe & oddity we had studied during the ramp up to the event. My wife did an excellent job with her photo efforts. She balanced her personal viewing time and planned equipment duties well. This was a source of much worry and discussion during the months prior.

I’ll mention a few surprises. I was impressed by the amount of light cast on the landscape with barely a sliver of the Sun remaining. I suspect the ambient sunlight to the south east was the major source. The rapid transition to peak darkness was dramatic.

In contrast, I noticed a clear reduction of heat radiation on my skin with about 50% coverage. It was a hot day. I wished I’d had more time to observe the animals.

I found it somewhat humorous how many folks took all of the important PSA’s about retina damage to heart. Before totality they bowed their heads to the ground when they did not have their gasses on while walking, standing and sitting.

What I learned most was, to the inexperienced, East Tennessee Moonshine travels faster than the Moon’s shadow.

Be careful!

Georgia- Jeannette Iriye (@i_fridrich)

We found a lovely scenic overlook facing west in Sky Valley, just outside Dillard, Georgia. Skies were clear with only minimal cloud cover until about 13:30, when heavy cloud cover began to build in the south/southeast. The clouds obfuscated the remainder of our view of the eclipse directly. It did get much cooler, windy, and the crickets were singing just prior to and during totality.

A partially eclipsed Sun versus clouds. Image credit and copyright: Jeannette Iriye.

South Carolina- Terri (@wizbee1)

We didn’t make it to South Carolina, and had to turn the plane back because of weather. Watched instead from Saint Mary’s Georgia. Did feel the temperature drop and experienced darkening but not in totality.

And us? We watched from the Pisgah Astronomical Research Institute in North Carolina as the shadow of the Moon draped over the landscape. The rolling afternoon clouds afforded only brief glimpses of the partially eclipsed Sun. Then, just prior to totality, we caught the final moments as the Sun withered to a brief diamond ring flash… and was gone. Magic! Unfortunately, the corona remained hidden behind high clouds for the 107 seconds of darkness, though we were treated to an unworldly 360 degree sunset below the cloud deck. Nocturnal mosquitoes, fooled by the false dusk, began their rounds, as a light “eclipse wind” kicked up.

Author and wife (@MyschaTheriault) standing in the shadow of the Moon, plus our view from the Pisgah Astronomical Research Institute (PARI) just before totality. Thanks to @Dayveesutton for snapping the pic!

Then, it was over. Got the eclipse bug? Well, another total solar eclipse crosses the U.S. in 2024… but you don’t have to wait that long, as we’ve got one coming right up crossing Argentina and Chile on July 2nd, 2019…

I’ll see you there!

Incredible Solar Eclipse Images From Our Readers

Totality of the August 21, 2017 solar eclipse, as seen from Waterloo, Illinois. Credit and copyright: Rob Sparks.

Holy moly, that was awesome! Incredible, fantastic, amazing…there just aren’t the words to describe what it is like to experience totality. While I’m trying to come down to Earth and figure out how to explain how wonderful this was, enjoy the beautiful images captured by our readers from across the US and those from across the world who traveled to capture one of nature’s most spectacular events: a total solar eclipse.

The images from those seeing partial eclipses are wonderful, as well, and we’ll keep adding them as they come in (update, we just got some from Europe too). Great job everyone!

Eclipse panorama. Got some cool Baily’s Beads and that prominence is nuts! Shot at 2000mm on an old Celestron 8in telescope! Credit and copyright: Kenneth Brandon.
2017 Solar Eclipse from Clayton GA, USA.
Celestron C8 Telescope on CGEM. Canon T3i (Modified IR enhanced), Solar Filter. Credit and copyright: Michael Bee.
The August 21, 2017 total solar eclipse over the Grand Tetons as seen from the Teton Valley in Idaho, near Driggs. ..This is from a 700-frame time-lapse and is of second contact just as the diamond ring is ending and the dark shadow of the Moon is approaching from the west at right, darkening the sky at right, and beginning to touch the Sun. The peaks of the Tetons are not yet in the umbral shadow and are still lit by the partially eclipsed Sun. ..With the Canon 6D and 14mm SP Rokinon lens at f/2.5 for 1/10 second at ISO 100. Credit and copyright: Alan Dyer.
Total Solar Eclipse, August 21, 2017 as seen from Tellico Plains, Tennessee. New City Expedition, photo by Igor Kuskovsky.
Total Solar Eclipse, Aug. 21, 2017, as seen from Charleston, South Carolina. Credit and copyright: Jason Major
Partial Eclipse montage from Charlottesville, Virginia. Credit and copyright: David Murr.
Partial Solar Eclipse August 21st 2017, as seen from Fullerton California USA. Sky: Partially Cloudy. Telescope: Nexstar 102 SLT Refractor, Camera: Fujifilm X-T1 @ Prime Focus. Credit and copyright: Jimmy CD.
From the total solar eclipse as seen in Columbia, Missouri, on Aug. 21, 2017. Credit and copyright: Wildhaven Creative.
Total Eclipse from Shaw Air Force Base (August 21, 2017). It was magical. Credit and copyright: Michael Seeley.

Partial solar eclipse, seen from the west coast of France, August 21, 2017. Credit and copyright: Frank Tyrlik.

Great American Eclipse, 21-08-2017. Silver Falls Oregon 10:17-10:19 local time. Raw straight out of the camera. 65mm Refractor / Canon 700D. Credit and copyright: Alexandra Hart.

New Study Says that Martian Weather May Get Snowy Overnight

Mars’ south polar ice cap. Credit: ESA / DLR / FU Berlin /

For decades, scientists have tried to crack the mystery of Mars’ weather patterns. While the planet’s atmosphere is much thinner than our own – with less than 1% of the air pressure that exists on Earth at sea level – clouds have been seen periodically in the skies above the surface. In addition, periodic snowfalls has been spotted over the years, mainly in the form of carbon dioxide snow (i.e. dry ice).

However, according to a new study by a team of French and American astronomers, Mars experiences snowfalls in the form of water-ice particles. These snowfalls occur only at night, coinciding with drops in global temperature. The presence of these storms, and the speed at which they reach the surface, is forcing scientists to rethink Mars’ weather patterns.

The study, titled “Snow Precipitation on Mars Driven by Cloud-Induced Night-Time Convection“, recently appeared in the journal Nature Geosciences. Led by Aymeric Spiga, a tenured lecturer at the Université Pierre et Marie Curie and a researcher at Laboratoire de Météorologie Dynamique in Paris, the team conducted numerical simulations of Mars’ cloudy regions to demonstrate that localized convective snowstorms can occur there.

Mars’ north polar ice cap, captured by NASA’s Mars Global Surveyor. Credit: NASA/JPL-Caltech/MSSS

For decades, scientists believed that Mars experienced snowfall in the form of frozen carbon dioxide (aka. dry ice), particularly around the south pole. But it has only been in recent years that direct evidence has been obtained. For instance, on September 29th, 2008, the Phoenix lander took pictures of snow falling from clouds that were 4 km (2.5 mi) above its landing site near the Heimdal Crater.

In 2012, the Mars Reconnaissance Orbiter revealed additional evidence of carbon-dioxide snowfalls on Mars. And there has also been evidence in recent years of low-falling snows, which appear to have helped shape the Martian landscape. These include a relatively young gully fan system in the Promethei Terra region of Mars, which researchers at Brown University determined were shaped by melting snow.

Further, in 2014, data obtained by the ESA’s Mars Express probe showed how the Hellas Basin (a massive crater) was also weathered by melting snows. And in 2015, the Curiosity rover confirmed that the Gale Crater (where it landed in 2012) was once filled by a standing body of water. According to the science team’s findings, this ancient lake received runoff from snow melting on the crater’s northern rim.

All of these findings were rather perlexing to scientists, as Mars was thought to not have a dense enough atmosphere to support this level of condensation. To investigate these meteorological phenomena, Dr. Spiga and his colleagues combined data provided by various Martian lander and orbiter missions to create a new atmospheric model that simulated weather on Mars.

Simulated view of the Gale Crater Lake on Mars. Credit: NASA/JPL-Caltech/ESA/DLR/FU Berlin/MSSS

What they found was that during the nights when Mars’ atmosphere became cold enough, water-ice particles could form clouds. These clouds would become unstable and release water-ice precipitation, which fall rapidly to the surface. The team then compared these results to localized weather phenomena on Earth, where cold dense air results in rains or snow falling rapidly from clouds (aka. “microbursts”).

As they state in their study, this information was consistent with data provided by Martian lander and orbiter missions:

“In our simulations, convective snowstorms occur only during the Martian night, and result from atmospheric instability due to radiative cooling of water-ice cloud particles. This triggers strong convective plumes within and below clouds, with fast snow precipitation resulting from the vigorous descending currents.”

The results also contradicted the long-held belief that low-lying clouds would only deposit snow on the surface slowly and gently. This was believed to be the case based on the fact that Mars has a thin atmosphere, and therefore lacks violent winds. But as their simulations showed, water-ice particles that lead to microburst snowstorms would reach the ground within minutes, rather than hours.

The Phoenix Mars Lander used a lidar device built by Teledyne Optech to detect snow in the Martian atmosphere in 2008. Credits: NASA

These findings indicate that Martian snowstorms also have a profound influence on the global transport of water vapor and seasonal variations of ice deposits. As they state further:

“Night-time convection in Martian water-ice clouds and the associated snow precipitation lead to transport of water both above and below the mixing layers, and thus would affect Mars’ water cycle past and present, especially under the high-obliquity conditions associated with a more intense water cycle.”

As Aymeric Spiga explained in an interview with the AFP, these snows are not quite what we are used to here on Earth. “It’s not as if you could make a snowman or ski,” he said. “Standing on the surface of Mars you wouldn’t see a thick blanket of snow—more like a generous layer of frost.” Nevertheless, these findings do point towards their being some similarities between the meteorlogical phenomena of Earth and Mars.

With crewed missions to Mars planned for the coming decades – particularly NASA’s “Journey to Mars“, scheduled for the 2030s – it helps to know precisely what kinds of meteorological phenomena our astronauts will encounter. While snowshoes or skis might be out of the question, astronauts could at least look forward to the possibility of seeing fresh snow when they wake up in their habitats!

Further Reading: AFP, Nature Geoscience