Is alien life purple?

When we look at Earth from space, the color green means life. It represents trees, grass, crops and everything that grows with the help of chlorophyll. Chlorophyll is a pigment found in nearly all plants that use photosynthesis to absorb energy from the sun and turn light into fuel. Chlorophyll also gives plants their green color. But in some environments on Earth without sunlight or oxygen, life uses infrared radiation for energy. And many of these bacteria are purple. What if life on other worlds uses infrared radiation instead of sunlight? According to a press release from Cornell University on April 16, 2024, we’d need to be looking for a light fingerprint of a purple planet.

Lígia Fonseca Coelho of Cornell University said:

Purple bacteria can thrive under a wide range of conditions, making it one of the primary contenders for life that could dominate a variety of worlds.

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Coelho is lead author of a new study titled Purple is the New Green. The Monthly Notices of the Royal Astronomical Society: Letters published the peer-reviewed study on April 16, 2024.

Looking for purple life

The researchers said that some of the next-generation telescopes in the works may be able to detect the purple light fingerprint of these worlds. With more than 5,500 exoplanets known, the telescopes will have many targets. Some of the future observatories that will study them include the Extremely Large Telescope and the Habitable Worlds Observatory. Both of these telescopes – not yet constructed – will look at the chemical composition of exoplanets in the habitable zone of their stars.

As scientists wait for the construction of these telescopes, they’re busy building a catalog of colors and chemical signatures. These colors could be what diverse organisms on other worlds present in an exoplanet’s reflected light. Co-author Lisa Kaltenegger of Cornell University said:

We need to create a database for signs of life to make sure our telescopes don’t miss life if it happens not to look exactly like what we encounter around us every day.

Alien life: purple is the new green

The Cornell scientists dove into their work of finding purple bacteria, including sampling from a pond right on campus. Technically, purple bacteria have a range of colors that include yellow, orange, brown and red. All these bacteria live in conditions that use infrared light – or heat – to survive. Their form of photosynthesis absorbs infrared without making oxygen.

Coelho said:

They already thrive here (on Earth) in certain niches. Just imagine if they were not competing with green plants, algae and bacteria: A red sun could give them the most favorable conditions for photosynthesis.

So, the researchers think purple bacteria would be a good match for cool, red dwarf stars. And red dwarf stars are the most abundant type of star in our Milky Way galaxy.

Using models simulating various conditions, the researchers found that:

… both wet and dry purple bacteria produced intensely colored biosignatures.

What if we find a purple world?

Coelho said they’ll be using their new tools to look for purple bacteria thriving on:

… a frozen Earth, an ocean world, a snowball Earth or a modern Earth orbiting a cooler star.

But if we spot a purple dot around a star, how do we know it means life is there? The first step is that researchers would try to rule out other sources that could be responsible for the purple hue. That would include colorful minerals, another area that researchers are cataloging.

If we did detect life in just one place in our vast universe, it would suggest that life might be widespread in the rest of the universe.

Kaltenegger said:

We are just opening our eyes to these fascinating worlds around us. Purple bacteria can survive and thrive under such a variety of conditions that it is easy to imagine that on many different worlds, purple may just be the new green.

Bottom line: Is alien life purple? Researchers from Cornell University think that as far as alien worlds go, purple may be the new green.

Source: Purple is the new green: biopigments and spectra of Earth-like purple worlds

Via Cornell University

The post Is alien life purple? Researchers look beyond Earth’s green first appeared on EarthSky.

• Carbon and oxygen ions are escaping Venus’ atmosphere into space. Scientists made the discovery when studying a previously unexplored region of Venus’ magnetosphere.
• The ESA and JAXA spacecraft BepiColombo analyzed this region during a Venus flyby. BepiColombo is en route to the planet Mercury.
• The findings also provide clues about the history of water escaping from Venus’ atmosphere over billions of years.

Venus’ atmosphere is leaking into space

Earth’s closest planetary neighbor, Venus – famous for its thick, noxious atmosphere – is leaking part of that atmosphere into space. That’s what a team of scientists from France, Germany, Austria and Japan said on April 12, 2024. BepiColombo, a mission of the European Space Agency (ESA) and Japan’s JAXA, made two flybys of Venus on its journey to Mercury. The spacecraft found carbon and oxygen escaping into space in a previously unexplored region of Venus’ magnetosphere. These gases are somehow being stripped away from the atmosphere’s upper layers.

The researchers published the peer-reviewed results of the Venus atmosphere analysis on April 12, 2024, in the journal Nature Astronomy.

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Escape from Venus’ atmosphere

BepiColombo’s visit to Venus on August 10, 2021, was brief, but it yielded important new information about the planet’s atmosphere. In fact, during this second flyby, the spacecraft studied a previously unexplored region of Venus’ magnetosphere. Basically, the magnetosphere is the region around a planet dominated by the magnetic field. And, if you could see it, it would look like a huge bubble around the planet. Magnetospheres aren’t always round, though. In fact, Earth’s magnetosphere is comet-shaped.

So, it was in an area of Venus’ magnetosphere that hadn’t been studied closely before that scientists found evidence of carbon and oxygen ions escaping from the planet’s upper atmosphere. An ion is an atom or group of atoms that bears one or more positive or negative electrical charges. Lina Hadid is a researcher at the National Centre for Scientific Research (CNRS) and the The Laboratory of Plasma Physics (LPP) in France and lead author of the study. She said:

This is the first time positively charged carbon ions have been observed escaping from Venus’ atmosphere. These are heavy ions that are usually slow moving, so we are still trying to understand the mechanisms that are at play. It may be that an electrostatic ‘wind’ is lifting them away from the planet, or they could be accelerated through centrifugal processes.

A weak magnetosphere

In general, Venus is rocky and of similar size and mass to Earth. Unlike Earth, however, it lacks a powerful magnetic field generated in its core. But it does have a magnetic field and magnetosphere, albeit much weaker than Earth’s. Scientists call it an induced magnetosphere. In Venus’ case, charged particles from the sun interact with the planet’s upper atmosphere to create the magnetosphere. In addition, a region of magnetic turbulence, called the magnetosheath, surrounds this weak magnetosphere. Overall, this has the effect of slowing down and heating the solar wind from the sun, which contains the charged particles.

The history of Venus’ atmosphere

BepiColombo used its Mass Spectrum Analyzer (MSA) and Mercury Ion Analyzer (MIA) to examine Venus’ magnetosphere. Both sensors are part of the Mercury Plasma Particle Experiment (MPPE) instrument package on Mio, the JAXA-led Mercury Magnetospheric Orbiter. The new data help scientists better understand the history of Venus’ atmosphere. Dominique Delcourt, a researcher at LPP and the Principal Investigator of the MSA instrument, said:

Characterizing the loss of heavy ions and understanding the escape mechanisms at Venus is crucial to understand how the planet’s atmosphere has evolved and how it has lost all its water.

In addition, scientists used Europlanet Society’s Sun Planet Interactions Digital Environment on Request (SPIDER) tools to track the carbon and oxygen ions as they escaped Venus’ atmosphere and moved through the magnetosheath. As Nicolas André of the Institute for Research in Astrophysics and Planetology (IRAP) and leader of the SPIDER service noted:

This result shows the unique results that can come out of measurements made during planetary flybys, where the spacecraft may move through regions generally unreachable by orbiting spacecraft.

Water loss in Venus’ atmosphere

These results also have implications for the loss of water from Venus’ atmosphere over billions of years. Many scientists, in fact, think Venus likely once had oceans. With this in mind, co-author Moa Persson at the Swedish Institute of Space Physics added:

Recent results suggest that the atmospheric escape from Venus cannot fully explain the loss of its historical water content. This study is an important step to uncover the truth about the historical evolution of the Venusian atmosphere, and upcoming missions will help fill in many gaps.

Bottom line: The BepiColombo spacecraft, headed for Mercury, flew past Venus and found that carbon and oxygen ions are escaping into space from Venus’ atmosphere.

Source: BepiColombo observations of cold oxygen and carbon ions in the flank of the induced magnetosphere of Venus

Via Europlanet Society

Read more: Amino acids on Venus? New study says it’s possible

Read more: Surprise! Plate tectonics helped create Venus’ hellscape

The post Venus’ atmosphere is leaking gases into space first appeared on EarthSky.

• The most massive stellar black hole in the Milky Way is now Gaia BH3. It has a mass 33 times that of our sun.
• Gaia BH3 is located 2,000 light-years away in the constellation Aquila, making it the 2nd-closest known black hole to Earth.
• The discovery challenges previous theories, suggesting that high-mass black holes may form from metal-poor stars, supported by Gaia’s observation of a metal-poor companion star to Gaia BH3.

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Meet Gaia BH3

The European Southern Observatory said on April 16, 2024, that its astronomers have helped confirm the discovery of the most massive stellar black hole yet discovered in our home galaxy, the Milky Way. They call the object Gaia BH3. And it isn’t the Milky Way’s most massive black hole. Instead, Sagittarius A*, the supermassive black hole at the Milky Way’s center, holds that title with some four million times our sun’s mass. Gaia BH3 has only 33 times our sun’s mass. It’s a pipsqueak in contrast to Sagittarius A*. But it’s the most massive black hole known in the Milky Way that formed from the collapse of a single star.

Gaia BH3 is relatively nearby at 2,000 light-years away. It’s the 2nd-closest known black hole to Earth. It’s located in the direction to the constellation Aquila the Eagle, a noticeable constellation in the Northern Hemisphere summer sky. Astronomer Pasquale Panuzzo, of the National Centre for Scientific Research (CNRS) in Paris, led the collaboration that discovered the massive black hole. He commented:

No one was expecting to find a high-mass black hole lurking nearby, undetected so far. This is the kind of discovery you make once in your research life.

The research study, led by Panuzzo, was published on April 16 in the journal Astronomy & Astrophysics.

The amazing Gaia mission

Now for a word of praise about Gaia, the European Space Agency’s astrometry mission, launched in 2013.

Gaia’s job is to scan the sky repeatedly, observing each of its targeted stars many times over. By the time of its 2nd data release in 2018, Gaia had measurements on 1.7 billion stars!

And the insights about our galaxy revealed by Gaia’s measurements have been nothing short of spectacular. For example, we’ve known our sun and all the stars in the Milky Way are moving continuously in great orderly masses around the center of our galaxy. We’ve known that, but we didn’t have many details about how each star moves, until Gaia. How could we? The data for so many stars would be (are) massive. Collecting the data, storing it and analyzing it requires today’s spacecraft and computer technologies. And that’s where Gaia comes in.

You can read many stories about new insights made possible by Gaia here.

How Gaia spied the black hole

Black holes are … black. No light escapes them. So how did Gaia discover our galaxy’s most massive stellar-mass black hole? It was able to do it because the hole imposes a “wobbling” motion on its companion star. In the course of Gaia’s acquiring measurements – and as astronomers analyzed those measurements – the wobble became noticeable to the astronomy world. And then, ESO said:

Data from the European Southern Observatory’s Very Large Telescope (ESO’s VLT) and other ground-based observatories were used to verify the mass of the black hole, putting it at an impressive 33 times that of the sun.

What are stellar-mass black holes?

As so often happens in astronomy, the theory of black holes preceded our discovery of them. The theory arose from the work of Albert Einstein in 1915, and so, throughout the early part of the 20th century, astronomers wondered if black holes did exist, and how we might find objects that emit no light. Astronomers agreed that, if black holes did exist, they probably formed when massive stars ran out of fuel and collapsed.

The first known black hole was seen in X-rays in 1964, in one of the first rocket flights needed to get high enough up that the X-rays weren’t blocked by Earth’s atmosphere. During this flight, astronomers discovered one of the brightest X-ray sources in the sky. Because it was located in the direction of the constellation Cygnus, they named it Cygnus X-1. This object – called Cyg X-1 for short – is now thought to have about 21 times our sun’s mass.

Do metal-poor stars lead to high-mass black holes?

So before Gaia GH3, we didn’t know of any black holes in our Milky Way galaxy with 33 stellar masses. But we knew such massive black holes existed, because they’d been found in other galaxies. But the formation of these black holes provided astronomers with a puzzle. These scientists’ statement explained:

[Astronomers] theorized that they may form from the collapse of stars with very few elements heavier than hydrogen and helium in their chemical composition. These so-called metal-poor stars are thought to lose less mass over their lifetimes and hence have more material left over to produce high-mass black holes after their death.

But evidence directly linking metal-poor stars to high-mass black holes has been lacking until now.

Stars in pairs tend to have similar compositions, meaning that BH3’s companion holds important clues about the star that collapsed to form this exceptional black hole. UVES data showed that the companion was a very metal-poor star, indicating that the star that collapsed to form BH3 was also metal-poor, just as predicted.

Bottom line: Astronomers have discovered the most massive stellar black hole yet discovered in our home galaxy, the Milky Way. They call the object Gaia BH3.

Source: Discovery of a dormant 33 solar-mass black hole in pre-release Gaia astrometry

Via ESO

The post Meet Gaia BH3, our galaxy’s most massive stellar black hole first appeared on EarthSky.

• New insights on the origin of Pluto’s heart-shaped feature came from scientists using numerical simulations.
• They said a cataclysmic collision created the western lobe of Pluto’s heart, called Sputnik Planitia. The impacting body was over 400 miles in diameter. It altered Pluto’s inner structure.
• These scientists now doubt Pluto has a subsurface ocean. Their simulations suggest the heart’s formation and position on Pluto can explained by a local mass excess from the impact, rather than ocean dynamics.

How Pluto got its heart

Scientists said yesterday they have new insights about how the dwarf planet Pluto got its giant heart-shaped feature. NASA’s New Horizons spacecraft first spied Pluto’s heart when it swept past the little world in 2015. Scientists named the heart-shaped feature Tombaugh Regio for Clyde Tombaugh, who discovered Pluto in 1930. But the heart on Pluto has puzzled scientists with its unique shape, geological composition and elevation. Now scientists have used numerical simulations to investigate the origins of the western lobe of Pluto’s heart, which they call Sputnik Planitia. They said a cataclysmic event created Pluto’s heart, a collision with a planetary body a little over 400 miles (650 km) in diameter.

Meanwhile, Sputnik Planitia itself covers an area of approximately 750 by 1,250 miles (1,200 by 2,000 km), equivalent to about 1/4 of Europe or the United States.

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These scientists – from the University of Bern in Switzerland and the University of Arizona in Tucson – published their findings in the peer-reviewed journal Nature Astronomy. They said their work suggests that the inner structure of Pluto is different from what was previously assumed.

And they said that, contrary to earlier assertions, there’s no reason to believe that Pluto – like so many small worlds in the outer solar system – has a subsurface ocean.

More than just heart-shaped

Pluto’s heart is a fantastic feature, and not just because it’s heart-shaped. It’s also covered in a brighter material than the rest of Pluto’s surface.

Plus, Sputnik Planitia – in the western lobe of the heart – is roughly 2.5 miles (4 km) lower in elevation than other parts of Pluto. Harry Ballantyne of University of Bern in Switzerland is lead author of the study. He commented:

The vast majority of Pluto’s surface consists of methane ice and its derivatives covering a water-ice crust. But the Planitia is predominantly filled with nitrogen ice, which most likely accumulated quickly after the impact due to the lower altitude.

Meanwhile, these scientists said, the eastern part of the heart is also covered by a similar but much-thinner layer of nitrogen ice. Scientists don’t entirely understand its origin. But they did suggest the origin of the heart’s western and eastern lobes are likely related.

Dead-on, or oblique?

The scientists’ statement said:

The elongated shape of Sputnik Planitia and its location at the equator strongly suggest that the impact was not a direct head-on collision but rather an oblique one. That’s according to Martin Jutzi of the University of Bern, who initiated the study.

Like several others around the world, the team used Smoothed Particle Hydrodynamics simulation software to digitally re-create the impacts. In their simulations, they varied both the composition of Pluto and its impactor, as well as the velocity and angle of the impactor.

The scientists said the simulations confirmed their suspicions about the oblique angle of impact. And, they said, it determined the composition of the impactor. Ballantyne explained:

Pluto’s core is so cold that the rocks remained very hard and did not melt despite the heat of the impact. And, thanks to the angle of impact and the low velocity, the core of the impactor did not sink into Pluto’s core. Instead, it remained intact as a splat on it.

The scientists said this core strength of Pluto – and the relatively low velocity of the impactor – were key to these simulations. They said lower core strength for Pluto would result in a symmetrical surface feature, not the heart shape observed by NASA’s New Horizons probe during its flyby of Pluto in 2015. Another study co-author, Erik Asphaug of the Lunar and Planetary Laboratory, has explored the idea of planetary “splats” to explain, for instance, features on the far side of Earth’s moon. He said:

We think of planetary collisions as incredibly intense events where you can ignore the details except for things like energy, momentum and density. But, in the distant solar system, the velocities of the impactors are much slower than closer to the sun. And solid ice, like that on Pluto’s surface, is strong. So you have to be much more precise in your calculations.

That’s where the fun starts.

What about Pluto’s subsurface ocean?

Not long ago, scientists thought Earth was the only place in our solar system with an ocean. Now we suspect several icy moons in the outer solar system are also water worlds. These alien oceans are different from Earth’s oceans: they’re not on the surfaces of the moons, but below the moons’ surface crusts of ice. Beginning in 2020, scientists began talking about evidence for another such ocean, this time not on an outer planet moon, but on the outer dwarf planet Pluto.

The evidence was based on what the scientists called “ripples” on Pluto’s surface.

The current study contradicts the idea of an ocean for Pluto. The scientists in Arizona and Switzerland say their simulation suggests a giant impact likely occurred early in Pluto’s history. Their statement explained:

But there was a problem. A giant depression like Sputnik Planitia is expected to slowly drift toward the pole of the dwarf planet over time due to the laws of physics, since it is less massive than its surroundings. Yet it has remained near the equator. The previous theorized explanation invoked a subsurface liquid water ocean, similar to several other planetary bodies in the outer solar system. According to this hypothesis, Pluto’s icy crust would be thinner in the Sputnik Planitia region, causing the ocean to bulge upward. And since liquid water is denser than ice, it would have caused a mass surplus that induces migration toward the equator.

The new study offers an alternative perspective, according to the authors.

Their simulations suggest that – as the impactor’s core material splatted onto Pluto’s core – it created a local mass excess. This excess can explain the migration of mass toward Pluto’s equator, without the need to call upon a subsurface ocean. Or, the team said:

… at most a very thin one.

Bottom line: The New Horizons spacecraft stunned the world in 2015, when it saw a heart-shaped feature on Pluto. New computer simulations suggest an impact created Pluto’s heart.

Source: Sputnik Planitia as an impactor remnant indicative of an ancient rocky mascon in an oceanless Pluto

Via University of Arizona

The post How Pluto got its heart first appeared on EarthSky.

Update! Image of asteroid 2013 NK4

NASA astronomers were able to obtain radar images of the large asteroid that passed Earth safely on Monday, April 15, 2024. They captured an image of the asteroid – named 2013 NK4 – using the Goldstone Radar in California on April 13. NASA said:

Radar narrow echoes probably establish that 2013 NK4 rotates very slowly, and the shape is bifurcated.

These observations suggest asteroid 2013 NK4 is probably a binary contact. That means it’s composed of two bodies or asteroids that have gravitated toward each other until they touch, resulting in this elongated shape. If a two-lobed asteroid sounds familiar to you, that’s because we’ve seen space rocks like this before. For example, there’s 4769 Castalia, discovered in 1989. It’s even larger at 1.4 kilometers (0.87 miles) in diameter and is also classified as a potentially hazardous asteroid. And another example is Arrokoth, visited by the New Horizons mission. Arrokoth looks a bit like a snowman and lies out in the Kuiper Belt.

Large asteroid is bigger than Apophis

Asteroid 2013 NK4 has a diameter of about 2,000 feet (610 meters). That makes it about twice as large as Apophis, the so-called doomsday asteroid that will pass closer than Earth’s artificial satellites in 2029. But 2013 NK4 passed us at a much greater distance. It was more than eight times the moon’s distance at its nearest to us. What’s so amazing about it? People with telescopes could watch it fly by Earth!

Closest approach for asteroid 2013 NK4 happened on Monday, April 15, 2024, at 14:51 UTC. But, due to its location in the sky, it was easier to see through a telescope on the nights of April 16 and 17. See finder charts below.

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The asteroid’s orbit

Because the asteroid occasionally passes near Earth and is a fairly large space rock, 2013 NK4 holds the scary-sounding designation of Potentially Hazardous Asteroid. However, we’ve known about asteroid 2013 NK4 since 2013 (thus the year designation in its name), and it has a well-defined orbit. There was absolutely no danger to Earth during its flyby.

2013 NK4 orbits the sun every 378 days. But its orbit is slightly more elliptical than ours. Its orbit goes out past Mars and then dives in between the orbits of Venus and Mercury. The asteroid sped past our planet at 36,909 miles per hour (59,400 km per hour) or 10.2 miles per second (16.5 km per second) relative to Earth.

Use a telescope to see the large asteroid

Using GoTo or computerized telescopes makes observing an asteroid easier than ever before. You can see an asteroid in the telescope eyepiece or screen as a slowly moving point of light in front of the background stars.

NASA studied NK4

According to NASA/JPL, astronomers imaged the space rock using the 230-foot (70-meter) DSS-14 Goldstone radar antenna in California from April 13-19. (See image above from April 13.) Also, on April 14, observations of this object were taken from Canberra, Australia, using NASA’s 34-meter (112-foot) DSS-35 dish antenna.

Scientists hope their images will help to refine the asteroid’s shape and size.

Large asteroid passed Earth! EarthSky’s Deborah Byrd created this 1-minute video summary for you.

Bottom line: A large asteroid – 2013 NK4, which spans about 2,000 feet (610 meters) across – safely passed Earth on April 15, 2024. It was visible in small telescopes on April 16 and 17. And check out the image from the Goldstone Radar in California from April 13. It shows a two-lobed object.

The post Large asteroid safely passed Earth: See pic here! first appeared on EarthSky.

• NASA’s Perseverance rover has sampled a Mars rock called Bunsen Peak. The rock is of high interest to mission scientists. The sample is the 24th that the rover has collected so far.
• The rock likely originated from an ancient lakeshore beach, from when Jezero crater used to be a lake billions of years ago.
• Bunsen Peak is rich in carbonate and silica, meaning it is ideal for the preservation of ancient microbial life, if it ever existed.

NASA’s Perseverance rover has been exploring inside Jezero crater on Mars. Scientists say this part of Mars was once a large lake. The rover’s findings have confirmed that idea, suggesting that the region was habitable a few billion years ago, at least for microbes. Perseverance has now picked up a sample of a rock, which the scientists call Bunsen Peak. And scientists are excited about this sample! They say the rock was once drenched in water and might have originated on a lakeshore beach. Mission scientists said on April 3, 2024, that the rock is just what they’d hoped to find when the rover landed back in 2021. Carbonate and silica in the rock make it ideal to preserve traces of microscopic life.

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Mars rock is ‘the kind we had hoped to find’

Perseverance has studied and sampled many different rocks during its mission so far. All of them provide valuable clues about what Mars used to be like billions of years ago. But this particular Mars rock, nicknamed Bunsen Peak, has mission scientists even a little more excited than usual. Why? Ken Farley is the project scientist for Perseverance at Caltech in Pasadena, California. As he explained:

To put it simply, this is the kind of rock we had hoped to find when we decided to investigate Jezero crater. Nearly all the minerals in the rock we just sampled were made in water; on Earth, water-deposited minerals are often good at trapping and preserving ancient organic material and biosignatures. The rock can even tell us about Mars climate conditions that were present when it was formed.

Perseverance has already found an abundance of organic compounds in rocks before. But this type of rock is especially good at preserving them, and even traces of life itself. This makes the samples obtained from the rock some of the most valuable so far in the mission.

An unusual rock from an ancient Martian beach

Mission scientists said that the rock likely originated on a beach, the shoreline of the ancient lake. They named the rock Bunsen Peak, after the mountain peak landmark in Yellowstone National Park. Even before analysis of the sample itself, which they named Comet Geyser, the mission team took notice of this interesting rock. About 5.6 feet (1.7 meters) wide and 3.3 feet (one meter) tall, it stood out from the surrounding landscape. One side had a rougher texture while the rest was smoother and fragmented in appearance.

It also wasn’t as dusty as rocks that are flatter, making it easier to analyze and obtain the sample with the rover’s drill. The rover studied the rock’s surface with its SuperCam spectrometers and X-ray spectrometer called Planetary Instrument for X-ray Lithochemistry (PIXL). Perseverance then ground (abraded) a small portion of the surface of the rock and re-analyzed it. The rover did this before it used its drill to obtain the rock core sample close to the abraded area.

Carbonate and silica could preserve traces of ancient microbial life

The initial analysis results were intriguing. Bunsen Peak is composed of at least 75% carbonate grains. Nearly pure silica binds the grains together. Why is this significant? As Sandra Siljeström, a Perseverance scientist from the Research Institutes of Sweden (RISE) in Stockholm, Sweden, explained:

The silica and parts of the carbonate appear microcrystalline, which makes them extremely good at trapping and preserving signs of microbial life that might have once lived in this environment. That makes this sample great for biosignature studies if returned to Earth. Additionally, the sample might be one of the older cores collected so far by Perseverance, and that is important because Mars was at its most habitable early in its history.

The Bunsen Peak sample is the 24th overall that Perseverance has collected so far. Of the sample tubes, 21 have rock cores, two contain regolith (broken up rock and dust) and one is a sample of atmospheric gases. It is also now the 3rd one collected while exploring the Margin Unit, a geologic area along the inner edge of Jezero crater’s rim.

Meet the Mars samples: Comet Geyser (Sample 24). Perseverance obtained this rock sample, named Comet Geyser, from the rock Bunsen Peak. Video via NASA/ JPL-Caltech/ MSSS/ JHU-APL/ Purdue/ USGS/ YouTube.

Mars rock provides more evidence for ancient lake

The findings support the hypothesis that a lake once filled Jezero crater. Perseverance has already found other abundant evidence for that scenario as well. In fact, it has been studying an ancient delta – just like deltas on Earth – where river water once broke through the crater wall and emptied into the crater. Briony Horgan, a Perseverance scientist from Purdue University in West Lafayette, Indiana, said:

We’re still exploring the margin and gathering data, but results so far may support our hypothesis that the rocks here formed along the shores of an ancient lake. The science team is also considering other ideas for the origin of the Margin Unit, as there are other ways to form carbonate and silica. But no matter how this rock formed, it is really exciting to get a sample.

Next, Perseverance is making its way to the westernmost portion of the Margin Unit. In particular, a location nicknamed Bright Angel is of interest to the science team. It may provide the first encounter with the much older rocks that make up the crater rim. Then, the rover will move to the top of the crater rim, which will take several months.

Bottom line: NASA’s Perseverance rover sampled an unusual Mars rock called Bunsen Peak. It is rich in carbonate and silica and likely came from an ancient lakeshore beach.

Via NASA

Read more: Perseverance rover reveals history of ancient habitable lake

Read more: Perseverance rover sprints to Martian delta

The post Did this Mars rock once lie along an ancient lakeshore? first appeared on EarthSky.

• The James Webb Space Telescope has now acquired images of three planet-forming disks. These are disks of gas and dust around young stars, where new planets might be forming.
• Webb didn’t see any baby planets in the disks. But, astronomers said, the planets might orbit too closely to their stars to be seen, even by Webb. Or they might be too faint.
• One astronomer said a particular disk – around the star HL Tau – “blew his mind.” He said he saw features of the disk resembling streams, clearly showing material flowing from the young star into the planet-forming disk.

Searching for baby planets in young planetary systems

Our own solar system – our sun and its family of planets – formed from a massive disk of gas and dust around the newborn sun. Likewise, astronomers have now seen and photographed many young planet-forming disks – called protoplanetary disks – over the years.

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Recently, the James Webb Space Telescope obtained its first images and observations of three young protoplanetary disks. Researchers at the University of Arizona led the new observations. They said that Webb didn’t detect any actual forming planets, but that is likely because the disks are still too young or the fledgling planets are too faint to be seen, even with Webb.

The research team, led by Jarron Leisenring at the University of Arizona’s Steward Observatory, published three peer-reviewed papers in The Astrophysical Journal on March 27, 2024. You can read them here, here and here.

Two additional papers are also being written, but are not yet published.

3 protoplanetary systems

The 3rd paper details some of the most interesting findings that Webb made. Specifically, the paper focuses on a protoplanetary disk around the young star HL Tauri, or HL Tau, 457 light-years away. Like most protoplanetary disks in young planetary systems, this one has multiple rings of material in the disk.

Scientists first saw those rings using the Atacama Large Millimeter/submillimeter Array (ALMA) radio telescope in the Atacama Desert, Chile. And the gaps between the rings are where new planets might be developing.

Additionally, Webb observed the protoplanetary disk systems SAO 206462 and MWC 758, as discussed in the other two papers.

Planets or no planets?

So, do any of these protoplanetary disks have baby planets? In order to examine them in the most detail possible, the researchers combined the new Webb images with previous ones from the Hubble Space Telescope and ALMA. This enabled the astronomers to see new details of the interactions between the disks and the envelopes of gas and dust that surround the young stars.

The observations, ultimately, did not reveal the presence of any planets. But the researchers said there may be a couple of reasons for that.

Kevin Wagner, also at the University of Arizona’s Stewart Observatory, is a co-author on the HL Tau paper and lead author on the MWC 758 paper. He said:

The lack of planets detected in HL Tau, and really in all three systems, tells us that the planets causing the gaps and spiral arms either are too close to their host stars or too faint to be seen with JWST. If the latter is true, it tells us that they’re of relatively low mass, low temperature, enshrouded in dust or some combination of the three, as is likely the case in MWC 758.

Comparison with other young planetary systems containing planets

Leisenring added:

While there is a ton of evidence for ongoing planet formation, HL Tau is too young with too much intervening dust to see the planets directly. We have already begun looking at other young systems with known planets to help form a more complete picture.

New views of proto-stellar envelopes

Even though Webb didn’t see any planets, it did make other important findings. For example, it obtained unprecedented views of the proto-stellar envelope. This envelope is a collapsing cloud of gas and dust – separate from the larger planet-forming protoplanetary disk – directly shrouding the young star. The gas and dust are just beginning to coalesce together in the envelope.

This was particularly evident in the images of HL Tauri, Wagner said:

When I saw the JWST images of HL Tau, they just blew my mind. I was expecting to see the disk or the rings, or maybe some planets in the rings, but instead, what we see are these features of the proto-stellar envelope resembling streams, clearly showing material flowing into the protoplanetary disk.

Leisenring also commented on the streams, saying:

We see a very complex and dynamic system with ‘streamers’ feeding material from the outer envelope into the inner regions of the disk, where we expect planets to be forming.

Bottom line: NASA’s Webb space telescope looked for baby planets in the protoplanetary disks of three young planetary systems. It didn’t find any so far. Scientists explain why.

Sources:

JWST/NIRCam Imaging of Young Stellar Objects. I. Constraints on Planets Exterior to the Spiral Disk Around MWC 758

JWST/NIRCam Imaging of Young Stellar Objects. II. Deep Constraints on Giant Planets and a Planet Candidate Outside of the Spiral Disk Around SAO 206462

JWST/NIRCam Imaging of Young Stellar Objects. III. Detailed Imaging of the Nebular Environment around the HL Tau Disk

Via University of Arizona

Read more: 1st planet-forming disk found in another galaxy

Read more: Astonishing image of planet-forming disk from ALMA

The post 3 young planetary systems revealed by Webb telescope first appeared on EarthSky.

• Previously undetected sub-micrometer particles have now been identified in the water vapor plumes of Saturn’s moon Enceladus.
• The plumes gush from cracks in the ice on Enceladus’ surface, suggesting a liquid ocean within this moon’s interior.
• The newly detected particles are in the same size range as some earthly bacteria, specifically those that live near hydrothermal vents in Earth’s oceans. Scientists say that Enceladus’ seafloor could have similar vents.

Sub-micrometer particles identified in Enceladus’ plumes

Enceladus is an intriguing little world, with a global ocean of salty water beneath its outer ice crust. Could there be life in this alien ocean? NASA’s Cassini spacecraft flew through and sampled the water vapor plumes that erupt through cracks in Enceladus’ icy surface. The spacecraft found a variety of organic compounds in the plumes. Now, three scientists in Poland say that Cassini may have discovered evidence for microorganisms. In late March, 2024, they described evidence of sub-micrometer-sized particles in the Cassini data of the plumes. Intriguingly, the size of the particles is consistent with some bacteria found around hydrothermal vents on seafloors on Earth.

The researchers published their peer-reviewed paper in the January-March issue of the journal Pomiary Automatyka Robotyka (PAR). The paper is also available on arXiv (March 23, 2024).

Jan Kotlarz and Katarzyna Kubiak are two of the researchers, at Lukasiewicz Institute of Aviation in Warsaw, Poland. Natalia Zalewska is the other researcher, at the Space Research Center of the Polish Academy of Sciences in Warsaw, Poland.

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Sampling the plumes on Enceladus

Cassini’s historic mission to Saturn and its moons ended in 2017. And, as might be expected, Cassini studied Enceladus repeatedly during multiple flybys.

The plumes erupt through large cracks in the icy crust at the South Pole called Tiger Stripes. Salty water from the ocean below makes its way up through the cracks and spews into space. In fact, Cassini actually flew through some of these plumes and sampled them directly. And, although its instruments weren’t designed to detect life itself, they did find many tantalizing clues about how habitable the ocean might be.

The ocean is similar to the ocean in the Antarctic covered by ice sheets. There are organic compounds, the building blocks of life, in the ocean as well. Cassini also found evidence for active hydrothermal vents on the seafloor. On Earth, those vents provide heat and mineral nutrients for a variety of life forms deep in the oceans.

Spectral analysis of Enceladus’ plumes

Cassini used its Ultraviolet Imaging Spectrograph (UVS) instrument to study particles in Enceladus’ plumes. The research team then later used ultraviolet spectral analysis and Mie solutions to identify and estimate the sizes of the new particles. The paper said:

Estimating particle size distribution on spectral data analysis is a common practice. One method is to compare the observed brightness of the scattering molecules with the Mie solutions of light scattering for Maxwell’s equations.

To describe the sub-micrometer particle size distribution in Enceladus plumes, we used ultraviolet hyperspectral data collected by the Cassini probe in 2009. Using this data, we calculated the ratio of the Saturn’s signal disturbed by the Enceladus transit to the Saturn’s pure signal. Then, using Mie solutions of Maxwell’s equations, we estimated effective cross-sections for particles with diameters between 10 nm and 2 um (micrometer). Effective cross-sections were estimated for 1024 UV wavelengths measured by Cassini UVIS.

Using the gradient-descent method, we estimated particle diameter distribution in plumes assuming that the modeled ratio of the disturbed to undisturbed signal should coincide with the spectrum observed by UVIS.

The paper itself goes into more technical detail as to how the particle sizes were determined.

Sub-micrometer particles reminiscent of bacteria

All of that is exciting and could point to Enceladus being not only geologically alive, but biologically as well. Cassini’s instruments couldn’t positively identify actual microbes, or pieces thereof, in the plumes. But what the three Polish scientists said they found in the data is interesting: sub-micrometer particles with diameters of 120–180 nm and 240–320 nm. These are consistent with three types of earthly bacteria in particular – Thermofilum, Thermoproteus and Pyrobaculum – that inhabit hydrothermal vents on Earth.

Also, previous studies had found ice particles in the plumes as small as < 0.4 um (micrometer). One um is a millionth of a meter. Scientists say those particles formed in the plume itself. Larger ice grains, however, came from the bottom of the ocean. As the researchers noted, particles smaller then 0.5 um are also similar to the size of single-celled bacteria that live in hydrothermal vents in Earth’s oceans:

Particles smaller than 0.5 um correspond to the size of single cells of thermophilic bacteria and archaea living inside Earth’s hydrothermal vents with temperatures near 80 °C. Thermophilic cells are smaller than typical 1–2 um microorganisms. The smallest cell sizes recognized in hyperthermophilic archaea are 0.17 um in diameter (Thermofilum sp.), 0.3 um in diameter (Thermoproteus sp. and Pyrobaculum), or disks 0.2–0.3 um in diameter and 0.08–0.1 um wide in Thermodiscus and Pyrodictium. The presence of methanogens in the ocean of Enceladus would result in the presence of particles in water plumes of sub-micrometer size, consistent with the diameter of the cells.

Is this evidence of life on Enceladus?

The results are intriguing, although not definitive yet. To be sure, more analysis is required to further determine just what the particles might be. Are they organic or something else? If they aren’t organic – composed of molecules known to be building blocks of life – then they can’t be cells as we know them on Earth. But if they are, then the possibilities become more interesting, indeed. Cassini discovered organic molecules on their own in the plumes before. Their origins could be either biological or non-biological. These newly-identified particles, however, are the right size to potentially be cells, whether living or dead.

As planetary astronomer Franck Marchis posted on X:

Three scientists from Poland have discovered two populations of sub-micron particles in Enceladus' hydrothermal vents, suggesting possible microbial life. Have we stumbled upon extraterrestrial life within our solar system through UV scattering? More observations of occultation… https://t.co/K3WnPS5BYe pic.twitter.com/z5alDX7t6x

— Franck Marchis (@AllPlanets) March 27, 2024

If the particles are biological, then the researchers speculate that they could be methanogens, microbes that produce methane. In 2021, scientists said that they found evidence of methane in the plumes, a surprising amount of it, in fact. This still isn’t proof of life yet, but methanogenic microbes do inhabit seafloor hydrothermal vents on Earth.

Comparison with bacteria from geysers on Earth

The paper concluded:

The main goal of our work was to confirm the presence of the sub-micrometer particles using far-ultraviolet part of the Cassini Ultraviolet Imaging Spectrograph Subsystem (UVIS) spectrum acquired during Enceladus passing in front of their parent planet in 2009 and compare results with known methanogenic archaea and bacteria sizes investigated by taking samples from hot (up to 80 °C) geysers on the Earth.

The result best-fit estimation of sub-micrometer particle diameters distribution give us two types of particles: characterized by diameters of 120–180 nm and 240–320 nm. Besides these two types we can see particles with diameters up to 1 um with a population of about 10–20 times lower than two main components. Also the micrometer-size particles discovered in many studies are present in our result.

The need expressed by Bedrossian et al. in 2017 that “detection of extant microbial life requires the ability to identify and enumerate micrometer-scale, essentially featureless cells” could be satisfied by ultraviolet measurement done by occultations.

Bottom line: A new study of Cassini data has revealed bacteria-sized particles in the plumes of Saturn’s ocean moon Enceladus. Could they be evidence of microbial life?

Source: Sub-Micrometer Particles Remote Detection in Enceladus’ Plume Based on Cassini’s UV Spectrograph Data

Read more: Watery plumes on Enceladus could hold signs of life

Read more: Enceladus’ ocean even more habitable than thought

The post Enceladus hosting cell-sized particles, a hint of life? first appeared on EarthSky.

Five years from tomorrow – on Friday, April 13, 2029 – a relatively large and extremely infamous asteroid named 99942 Apophis will zoom past Earth. It’ll be easily visible to the eye. Many astronomers will study it. But Apophis will not strike us in 2029. For a time, initial observations suggested that if Apophis passed through a region of space only half a mile wide (about 800 meters) – dubbed a “keyhole” by astronomers – at the 2029 pass, then it might strike us exactly seven years later, on April 13, 2036. But, by 2006, that idea was disproven.

Apophis is exciting! But it’s not frightening. Here’s the updated story on this amazing asteroid.

And you pronounce Apophis as uh-pah’-fs.

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Location, location, location

Apophis is a space rock about 1,100 feet (340 meters) across. Calculations in recent years have proven the asteroid will safely glide past Earth in both 2029 and 2036. In 2029, Apophis should pass at a nominal distance of 19,662 miles (31,643 km) from the Earth’s surface. That’s in contrast to the moon’s average distance of about 238,000 miles (384,000 km). And it’s closer than many Earth-orbiting satellites. As the asteroid encounters Earth’s gravitational field in 2029, one result could be asteroid-quakes on Apophis. This passage will also change the orbit of Apophis slightly.

Not everyone will be able to see Apophis in 2029. If you are in Australia, southern Asia, southern Europe, or Africa, you will have a front-row seat to see this asteroid when it is at its brightest. As the asteroid moves farther from the Earth and dims, it becomes visible in eastern South America. As evening falls along the east coast of North America, the asteroid will be a telescopic object located in a part of the sky about 15 degrees north of the Pleiades. An ephemeris for the asteroid is here.

Discovery of Apophis

Astronomers at Kitt Peak National Observatory near Tuscon, Arizona, discovered Apophis on the evening of June 19, 2004. The team of Dave Tholen, Fabrizio Bernardi, and the late Roy Tucker were searching for asteroids low in the western sky. They were specifically looking for objects in the direction of the sun. The asteroid they found was originally designated 2004 MN₄. It was 57 degrees from the sun, unusually close for an asteroid.

But astronomers quickly recognized this asteroid was different from most. It orbits the sun in less than one Earth-year (Apophis takes 323.6 days to orbit the sun. Earth takes 365.3 days). And Apophis gets nearly as close to the sun as the planet Venus, then heads out to just beyond Earth’s orbit. Its orbit defines Apophis as what astronomers call an Aten-class asteroid.

During its orbit, Apophis can pass very close to the Earth. This fact quickly caught the attention of astronomers worldwide. By December 2004, they had enough data to make a rough calculation of the future orbit of the asteroid. And they found it had a 2.7% chance of hitting the Earth in April 2029, on Friday the 13th. That same month, Apophis moved to the top of the list of potentially hazardous asteroids.

You can imagine the media frenzy that resulted.

Probability of collision reduced by precision

It took several more years of studying this asteroid to learn it would not strike Earth in 2029. The fact is, an asteroid’s orbital path can be changed slightly, every time it passes near another astronomical object. And it can change by what’s called the Yarkovsky effect, a minor push on the asteroid, caused by sunlight.

Both are known effects. But astronomers can determine the extent of these effects only after careful measurement of an asteroid’s positions over the course of years.

And observing this asteroid year after year isn’t as straightforward as you might think. Some years, the asteroid isn’t observable because it appears too close to the sun, as seen from the Earth. So astronomers imaged Apophis extensively whenever it was visible. And, by 2006, they were able to determine that Apophis won’t hit the Earth in 2029.

Whew, we dodged that one!

What about 2036?

But what about the next close approach in 2036? That possibility was eliminated in 2013.

In early March of 2013, all eyes turned toward Apophis as the asteroid made a relatively close sweep (though not nearly as close as in 2029) to our planet on March 6. The Goldstone Deep Space Communications Complex tracked the asteroid for about two weeks around the closest approach. Researchers at the Green Bank Telescope took observations, coordinating with Goldstone because the use of these two telescopes together allows the data to be sharper. The coordination between the two telescopes meant that Goldstone was transmitting data while Green Bank was receiving, performing what is known as a bistatic experiment that doubled the strength of the received signal. Marina Brozovic of NASA’s Jet Propulsion Laboratory explained:

Apophis made a [close approach in 2013] with Earth, it was still nearly 10.6 million miles (17 million km) away. Even so, we were able to acquire incredibly precise information about its distance to an accuracy of about 490 feet (150 meters).

Later calculations let NASA scientists announce on March 26, 2021, that Earth is safe from an impact with the relatively large asteroid for at least the next 100 years. Radar observations taken at NASA’s Goldstone Deep Space Communications Complex in California and the Green Bank Observatory in West Virginia have officially ruled out an impact in 2068, the only year out of the next 100 that previously showed a slight risk. Earlier observations had ruled out impacts during the upcoming 2029 and 2036 flybys.

Davide Farnocchia of NASA’s Center for Near-Earth Object Studies said:

A 2068 impact is not in the realm of possibility anymore, and our calculations don’t show any impact risk for at least the next 100 years.

Apophis is no longer listed as a risk

This new analysis means that Apophis is no longer on the Sentry Impact Risk Table, which is a list of objects that pass so close by Earth that astronomers have not yet been able to rule out a possible strike.

This campaign not only helped us rule out any impact risk, but it also set us up for a wonderful science opportunity in 2029.

The images seen at top are the product of the collaboration. Brozovic went on to describe the excellent quality achieved through the collaboration, which she called:

… a remarkable resolution, considering the asteroid was 10.6 million miles (17 million km) away, or about 44 times the Earth-moon distance. If we had binoculars as powerful as this radar, we would be able to sit in Los Angeles and read a dinner menu at a restaurant in New York.

More images from 2021

The image, taken by the Virtual Telescope Project in Europe, shows Apophis as a distant bright dot against a backdrop of stars.

The photo was taken using a telescope mounted on a robotic arm. The astronomers used a single 300-second exposure shot to capture the image, seen below pic.twitter.com/6y5dIU7d7Y

— ? ???? ? (@TeahCartel) March 5, 2021

The Virtual Telescope Project, based in Rome, Italy, captured asteroid (99942) Apophis on March 2, 2021. The asteroid shows as a dot – while the stars around it show as streaks – because the telescope was tracking the asteroid’s motion. It is moving through space with respect to Earth at 2.894 miles/sec (4.658 km/sec). Image via Virtual Telescope.

Astronomers also studied asteroid Apophis using NASA’s NEOWISE infrared space telescope in April 2021. This is the same telescope that discovered 2020’s favorite comet, Comet NEOWISE. They found the asteroid is about 1181 feet (360 meters) across and reflects about 30% to 50% of the light that strikes it. They also suspect the asteroid is “significantly elongated”. The NEOWISE report is here.

A gentle effect that pushes a rock

Astronomers in Hawaii studied how Yarkovsky acceleration, or pushes due to sunlight, would change Apophis’ orbit. In some instances, acceleration – a change in an object’s speed and direction through space – can help avoid a collision. Studies of Yarkovsky acceleration as related to asteroid Apophis suggest this is the case for this asteroid.

Astronomer Dave Tholen and colleagues suggest that Apophis is drifting more than 500 feet (about 152 meters) per year from its expected position in its orbit. These observations aren’t easy to obtain and analyze. Factors such as the asteroid’s distance at the time of observation, its composition, its shape, and its surface features all affect the outcome.

Read more about the Yarkovsky effect: Pushing asteroids around with sunlight

Apophis between now and then

Apophis is now in a part of the sky that is not observable from Earth. It will remain so until we see it again in 2029.

NASA’s OSIRIS-REx was a historic space mission, which brought the first samples from asteroid Bennu back to Earth. The spacecraft remains in good condition and still has a quarter of its fuel left. So NASA has redirected the craft to a new destination. It’s now on its way to the asteroid Apophis. After a long journey, the craft will reach Apophis in April 2029, just as the asteroid is sweeping past Earth.

And NASA has given the mission a new name. It’s now called OSIRIS-APEX, short for Origins, Spectral Interpretation, Resource Identification, and Security – Apophis Explorer.

Bottom line: Five years from now on April 13, 2029, the asteroid Apophis will zoom safely past the Earth. This much-anticipated event is a “must-see” for all.

Via NASA

Via CNEOS

Read more: OSIRIS-APEX mission is headed to asteroid Apophis

Read more about the Yarkovsky effect: Pushing asteroids around with sunlight

The post Asteroid Apophis to sweep close 5 years from tomorrow first appeared on EarthSky.

• Astronomers have detected what appears to be a glory – the same optical phenomenon you sometimes see out the window of an airplane – on on exoplanet, or planet orbiting a distant star.
• Glories are common on Earth, and spacecraft have seen them on Venus. But, if confirmed, this will be the first time astronomers have seen a glory outside of our solar system.
• Glories are a natural circular rainbow-like phenomenon that only occur in certain atmospheric conditions.

Have you ever seen a glory? Glories are colorful, concentric rings of light that form only under certain conditions. You can often see them while looking out an airplane window. They’re fairly common to see on Earth. And astronomers have also seen glories on Venus. But on April 5, 2024, scientists said they’ve detected the first-ever glory outside our solar system, on an exoplanet – or planet orbiting another star – some 637 light-years away. The exoplanet is called WASP-76b, and it’s an ultra-hot gas giant.

They said they spotted the glory using data from two different space observatories: ESA’s CHaracterising ExOPlanet Satellite (Cheops) and NASA’s Transiting Exoplanet Survey Satellite (TESS).

The researchers published their peer-reviewed findings in the journal Astronomy & Astrophysics on April 5, 2024.

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1st glory on an exoplanet?

If this is really a glory – still to be fully confirmed – it will be the first one ever seen outside of our solar system. Olivier Demangeon is an astronomer at the Institute of Astrophysics and Space Sciences in Portugal, and lead author of the new study. He said:

There’s a reason no glory has been seen before outside our solar system; it requires very peculiar conditions. First, you need atmospheric particles that are close-to-perfectly spherical, completely uniform and stable enough to be observed over a long time. The planet’s nearby star needs to shine directly at it, with the observer – here Cheops – at just the right orientation.

The glory appears to be located between the day side and night side of the planet. Similar to glories seen here, it likely occurs when sunlight is reflected off clouds made of a uniform substance. What that substance is on WASP-76b, however, is still unknown.

Hints of the glory phenomenon

So, how did the astronomers detect the glory? The first hints came from observation of the planet as it transited – passed in front of – its star as seen from Earth. The limbs of the planet – the outermost edges – looked “wonky.” The researchers made 23 observations of WASP-76b over three years. During that time, they noticed something unusual. They saw more than the expected amount of light coming from the planet’s eastern terminator, where the day side meets the night side. What might explain the change in brightness?

The researchers said that a glory can explain the odd observations. Demangeon said:

This is the first time that such a sharp change has been detected in the brightness of an exoplanet, its “phase curve.” This discovery leads us to hypothesise that this unexpected glow could be caused by a strong, localised and anisotropic (directionally dependent) reflection … the glory effect.

A hellish world

WASP-76b is a gas giant planet, like Jupiter and Saturn, 637 light-years from Earth. It is, in fact, almost twice the twice the size of Jupiter. But about 10% less massive, however. In our solar system, the giant planets all orbit far away from the sun. But WASP-76b is what astronomers call a hot Jupiter. It orbits its sun-like star 12 times closer than Mercury orbits our sun. No wonder it’s so hot!

It is tidally locked to its star, so one side is always in daylight while the other is in darkness. It is so hot, up to 2,400 degrees Celsius (4,300 degrees F) on the dayside, that scientists say it probably rains molten iron. Rocks on the day side would melt. They then evaporate and condense back on the night side. This could create clouds composed of iron particles that would then drip molten iron rain.

Co-author Matthew Standing at ESA said:

What’s important to keep in mind is the incredible scale of what we’re witnessing.

WASP-76b is several hundred light-years away, an intensely hot gas giant planet where it likely rains molten iron. Despite the chaos, it looks like we’ve detected the potential signs of a glory. It’s an incredibly faint signal.

The science of a glory on an exoplanet

Why is finding a glory on an exoplanet significant? First, it’s already a relatively rare phenomenon in our own solar system overall. So finding glories on exoplanets shows that they can happen elsewhere, too. It also provides clues about WASP-76s’s atmosphere. It means there must be clouds made of perfectly spherical droplets. The observations so far show that they either can last more than three years or the clouds are being constantly replenished. That in turn requires temperatures to be stable over long periods of time.

In addition, being able to detect glories will help astronomers see other faint phenomena including glints of sunlight on oceans or lakes on exoplanets.

There is also just the intrigue and satisfaction of finding something new and unique. Demangeon explained:

I was involved in the first detection of asymmetrical light coming from this weird planet, and ever since I have been so curious about the cause. It has taken some time to get here, with moments where I asked myself, “Why are you insisting on this? It might be better to do something else with your time.” But when this feature appeared out of the data, it was such a special feeling, a particular satisfaction that doesn’t happen every day.

More observations needed to confirm

Additional observations are needed to know for sure that this is a glory, as Theresa Lüftinger, Project Scientist for ESA’s upcoming Ariel mission, which will study the chemical makeup of exoplanets, noted:

Further proof is needed to say conclusively that this intriguing ‘extra light’ is a rare glory. Follow-up observations from the NIRSPEC instrument onboard the NASA/ESA/CSA James Webb Space Telescope could do just the job. Or ESA’s upcoming Ariel mission could prove its presence. We could even find more gloriously revealing colors shining from other exoplanets.

Bottom line: For the 1st time, astronomers say they have detected a glory on an exoplanet. Glories are a natural phenomenon, but until now seen only on Earth and Venus.

Source: Asymmetry in the atmosphere of the ultra-hot Jupiter WASP-76 b

Via ESA

Read more: Perfect airplane glory

Read more: Space rainbow: Glory seen in Venus atmosphere

The post Rainbow-like glory on an exoplanet is 1st-ever detected first appeared on EarthSky.