Tag Archives: jupiter

Why does Jupiter have so many darn moons?

Credit: Pixabay.

Jupiter is monstrously large, so much so that it is more than twice as massive as all other planets in the solar system combined. Consequently, it has an equally massive gravitational pull that helped it capture a myriad of satellites.

By the latest count, the gas giant has 79 confirmed moons. That’s two moons shy of Saturn’s count of 82 confirmed moons. But the race is still on for which planet has the largest entourage since astronomers keep constantly discovering new ones.

Saturn stole the crown from Jupiter in 2019 when astronomers discovered 20 new moons. But Jupiter isn’t done for — far from it. Twelve new satellites were discovered in 2017 alone around Jupiter by researchers affiliated with the Carnegie Institution for Science thanks to recent advances in large digital cameras and astronomical techniques. What’s more, there are good reasons to believe that Jupiter has, by far, the largest number of moons in the entire solar system.

Orbits of Jupiter’s 71 irregular satellites as of 1 January 2021, each of them labeled. Credit: Nrco0e / Wikimedia Common.

In September 2020, astronomers from the University of British Columbia identified 45 candidate moons with a diameter of over 800 meters. The researchers only surveyed a tiny area of the sky though and when they extrapolated their data, they concluded that there could be more than 600 of these tiny moons orbiting Jupiter.

These candidates are currently under investigation, which will take a lot of time since it takes quite a lot of telescope time to reliably verify their orbits. But while scientists are kept busy with cataloging huge boulders zipping across Jupiter’s motion, it’s perhaps a good time to find out why Jupiter has many moons. What’s so special about it?

Thanks for the free lunch, sucker!

The reason why Jupiter is such a moon magnet has a lot to do with its stupendous mass, equal to more than 300 Earths. Earth’s one and only Moon likely formed billions of years ago after a huge proto-planet slammed into primordial Earth. But most moons, especially around gas giants, don’t have such an exciting history. Like a school bully, Jupiter and other gargantuan planets like it are in the habit of ‘capturing’ rocky objects ranging from smallish asteroids to full-fledged mini-planets with volcanic activity, such as Io.

Jupiter, as well as other distant gas giants in the solar system such as Saturn and Neptune, has another ace up its sleeve. Not only does it have a very strong gravitational pull thanks to its mass, but it is also quite far away from the Sun. It’s about 5 times farther away from the Sun than Earth is, completing a full orbit every 11.86 years.

This great distance allows Jupiter to exert a larger area of influence or control as the Sun’s gravitational influence weakens the farther away you travel from it. With such a wide net cast, it’s no wonder that Jupiter has moons orbiting it as far away as 23.5 million miles, as is the case for Pasiphae and Sinope. Meanwhile, Venus and Mercury, the two closest planets to the sun in the solar system, have no moons at all, while Earth has a measly one to speak of and Mars as two tiny satellites.

Also important, albeit to a lesser degree, is the gas giant’s shape. A cosmic body that is regularly round will have a more stable orbit than a potato-shaped one. Jupiter is almost perfectly round and that may have helped it capture some additional small satellites, especially in its lower orbit.

Big rocks around a gas giant

Montage of Jupiter and the Galilean satellites, Io, Europa, Ganymede, and Callisto, all photographed by Voyager 1.

Of Jupiter’s many moons, collectively known as Jovian moons, the four largest particularly stand out. These moons — Callisto, Io, Europan, and Ganymede — are often called Galilean moons in honor of Galileo Galilei, the Italian astronomer who first discovered them in 1610. The moons themselves are each named after lovers and favorites of the god Jupiter (Zeus); and since 2004, also after their descendants. In the future, however, astronomers may run out of mythological beings to name Jovian moons by.

Three of these four moons are larger than Earth’s Moon and one, Ganymede, is the largest moon in the solar system. In fact, all you need is a pair of good binoculars or a retail telescope to see all four of these largest moons of Jupiter, which are all at least 3,100 kilometers (1,900 mi) in diameter.

Although the four Galilean moons comprise a small proportion of Jupiter’s of 79 confirmed satellites, they collectively sum 99.999% of the total mass orbiting Jupiter, including the ring system. The Galilean moons are also a lot more quirky than their more puny Jovian cousins. For instance, Io is packed with active volcanoes and Europa may harbor life in a liquid ocean covered by thick ice.

All other Jovian moons are less than 250 kilometers (160 miles) in diameter, although most barely exceed 5 kilometers (3.1 miles).

While the Galilean moons are believed to have formed along with Jupiter from its circumplanetary disk — a ring of gas and dust — the outer, irregular moons are believed to have originated from captured asteroids.

And over the course of its long history, Jupiter likely harbored many other moons, which are now long gone. Some were destroyed by mechanical fracturing during the capture or during collisions with other asteroid-like objects, some simply drifted away out of Jupiter’s clutches. You win some, you lose some.

In the dark and gloomy part of the solar system that Jupiter calls home, there is an abundance of large asteroids (with a diameter greater than one kilometer), so it’s reasonable to believe the number of Jovian moons could swell in the future. But in the meantime, scientists are still busy identifying the gas giant’s existing moons. It may not be long before Jupiter reclaims its crown, rising once again to the top as the planet with the most moons.

Astronomers find moon-forming disk around exoplanet

Artist impression of the circumplanetary disk surrounding PDS 70c. Credit: ESO/ALMA.

In the early 1990s, scientists knew about a handful of exoplanets (planets outside the solar system). Since then, more than 4,000 exoplanets have been confirmed with thousands more up for investigation. Indeed, technology and astronomers’ skills have grown tremendously. So much so that we can now peer inside certain exoplanets and determine their composition or atmosphere, as well as tell whether some have moons orbiting them. Now, astronomers have upped their game once more, reporting the discovery of a disk of gas and matter surrounding a planet that is supposed to coalesce into a new moon.

The novel discovery was made in the PDS70 star system, located relatively closeby, about 370 light-years from Earth in the constellation Centaurus. Astronomers working with the European Southern Observatory’s (ESO) Atacama Large Millimeter/submillimeter Array (ALMA) found that the system consists of at least two huge Jupiter-sized planets, along with a dust-rich circumstellar disk about as large in width as the distance from the Sun to Earth’s orbit.

Both gas giants feed on the dust disk, funneling material towards them by gravity. So, essentially, these young planets, unceremoniously named PDS 70b and PDS 70c, are still a work in progress.

“More than 4,000 exoplanets have been found until now, but all of them were detected in mature systems,” says Miriam Keppler, co-author of the new study and researcher at the Max Planck Institute for Astronomy in Germany. “PDS 70b and PDS 70c, which form a system reminiscent of the Jupiter-Saturn pair, are the only two exoplanets detected so far that are still in the process of being formed.”

This image shows wide (left) and close-up (right) views of the moon-forming disk surrounding PDS 70c, a young Jupiter-like planet nearly 400 light-years away. The close-up view shows PDS 70c and its circumplanetary disk center-front, with the larger circumstellar ring-like disk taking up most of the right-hand side of the image. Credit: ALMA (ESO/NAOJ/NRAO)/Benisty et al.

But the researchers noticed something else too. When they zoomed in on the high-resolution observations in submillimeter light performed by ALMA, the astronomers uncovered a circumplanetary disk surrounding PDS 70c. The disk was so well defined that its size could be ascertained, being roughly 500 times larger than Saturn’s rings.

This moon-making disk is most likely made of the same material as the much larger looming circumstellar disk that was collected by PDS 70c as the planet swept its orbit. Over millions of years, the researchers believe all of this matter will join together to form a new satellite, similar to how planets form around the sun from the much larger circumstellar disk. In fact, there may be enough material to make three satellites the size of Earth’s Moon.

Subsequent observations should serve to confirm that the object in question around PDS 70c is indeed a circumplanetary disk. If that’s the case, these observations could prove invaluable in clarifying how exomoons form and validating existing theories concerning their formation. ESO’s Extremely Large Telescope (ELT), currently under construction on Cerro Armazones in the Chilean Atacama desert, will be ideal for this task.

“The ELT will be key for this research since, with its much higher resolution, we will be able to map the system in great detail,” says co-author Richard Teague, a co-author and Submillimeter Array (SMA) fellow at the CfA.

The findings were reported in The Astrophysical Journal Letters.

NASA’s Juno to make closest flyby to Jupiter’s largest moon

NASA’s Juno spacecraft will fly at only 1,038 kilometers (645 miles) from the surface of Jupiter’s largest moon, Ganymede, tomorrow, June 7. It will be the closest-known flyby since the Galileo spacecraft made its penultimate close approach more than a decade ago and it’s expected to yield valuable insights into Jupiter’s moon. 

Left to right: The mosaic and geologic maps of Jupiter’s moon Ganymede were assembled incorporating the best available imagery from NASA’s Voyager 1 and 2 spacecraft and NASA’s Galileo spacecraft. Image credit: NASA

Juno’s science instruments will start gathering data about three hours before the spacecraft’s closest approach. The measurements will provide valuable information into the Moon’s composition, ionosphere, magnetosphere, and ice shell. They will also benefit future missions to the Jovian system, which includes Jupiter, its rings and moons. 

“Juno carries a suite of sensitive instruments capable of seeing Ganymede in ways never before possible,” Scott Bolton, Juno’s main investigator, said in a statement. “By flying so close, we will bring the exploration of Ganymede into the 21st century, both complementing future missions with our unique sensors and helping prepare for the next generation of missions to the Jovian system.”

Juno’s flyby is powered by solar energy and will send the information and images about this moon to Earth. Due to the speed of the flyby, the moon will go from being a point of light to a viewable disk, then back to a point of light in about 25 minutes. Ganymede is larger than the planet Mercury and it’s the only moon in the solar system with its own magnetosphere.

With an ultraviolet spectrograph, a microwave radiometer, and an infrared mapper, Juno will peer into Ganymede’s water-ice crust, gathering data on its composition and temperature. Bolton said the MWR will provide information of how the composition of how the composition and structure of the moon’s ice shell varies with depth. 

NASA will also use the signals from Juno’s wavelengths to perform a radio occultation experiment to probe the moon’s tenuous ionosphere – the outer layer of an atmosphere where gases are excited by solar radiation to form ions. This will help to understand the connection between the moon’s ionosphere, its magnetic field, and Jupiter’s magnetosphere. 

At the same time, Juno’s navigation camera, originally tasked to help the orbiter on course, will be in charge of collecting information on the high-energy radiation environment in the region near Ganymede. Heidi Becker, Juno’s radiation monitoring lead, explained that a special set of images will be collected as part of that experiment. 

Exploring Jupiter

Juno’s main goal is to understand the origin and evolution of Jupiter. Underneath its dense cloud cover, Jupiter safeguards secrets to the fundamental processes and conditions that governed our solar system during its formation. As the main example of a giant planet, Jupiter can also provide critical knowledge for understanding the planetary systems being discovered around other stars.

The mission is the second spacecraft designed under NASA’s New Frontiers Program. The first was the Pluto New Horizons mission, which flew by the dwarf planet in July 2015 after a nine-and-a-half-year flight. Juno will investigate the existence of a solid planetary core, map Jupiter’s magnetic field, measure the amount of water in the atmosphere and observe the planet’s auroras. 

Just like the sun, Jupiter is mostly hydrogen and helium, so it must have formed early, capturing most of the material left after our star came to be. But it’s so far unclear how this happened. Jupiter’s giant mass allowed it to hold onto its original composition, providing with a way of tracing our solar system’s history.

Jupiter’s Supersonic Stratospheric Winds Make it a Unique Beast

Using the aftermath of a comet collision in 1994 astronomers have measured the winds blowing across Jupiter‘s stratosphere for the first time. The team has discovered that these winds raging around the middle atmosphere of the solar system’s largest planet are incredibly powerful–reaching speeds of up to 400 metres per second at the poles.

The team’s findings represent a significant breakthrough in planetary metrology and mark the gas giant out as what the team are describing as a ‘unique metrological beast in the solar system.’

This image shows an artist’s impression of winds in Jupiter’s stratosphere near the planet’s south pole, with the blue lines representing wind speeds. These lines are superimposed on a real image of Jupiter, taken by the JunoCam imager aboard NASA’s Juno spacecraft. (ESO/L. Calçada & NASA/JPL-Caltech/SwRI/MSSS)

To conduct the research the astronomers diverged from the usual methods used to measure the winds of Jupiter. Previous attempts to measure the gas giant’s winds have hinged on measuring swirling clouds of gas–seen as the planet’s distinctive red and white bands–but this method is only effective in measuring winds in the lower atmosphere. Whereas, by using aurorae at Jupiter’s poles researchers have been able to model winds in the upper atmosphere. But, both of these methods, even when used in conjunction, have left the winds in the middle section of the gas giant’s atmosphere–the stratosphere– something of a mystery.

That is until now. This team of astronomers used the Atacama Large Millimetre Array (ALMA) to track molecules left in Jupiter’s atmosphere by the collision with the comet Shoemaker-Levy 9 in 1994.

“We had to use ALMA’s ability to quickly map Jupiter’s spectral emission at very high spatial and spectral resolution in the submillimeter and observe the Doppler shifts induced by the winds on the spectral line we targeted,” team leader Thibault Cavalié,  Laboratoire d’Astrophysique de Bordeaux, France, exclusively tells ZME Science. “We could deduce the wind speeds just like you could deduce the speed of a passing fire engine by the change in frequency of its siren. This spectral line is formed in the stratosphere, giving us access to the winds at this altitude.

“It is the first time we achieve measuring directly winds in the stratosphere of Jupiter, which lacks visual tracers such as clouds.”

Thibault Cavalié,  Laboratoire d’Astrophysique de Bordeaux, France.

Cavalié explains that the team had to use ALMA’s ability to quickly map Jupiter’s spectral emission at very high spatial and spectral resolution in the submillimeter and observe the Doppler shifts induced by the winds on the spectral line they targeted.

“We could deduce the wind speeds just like you could deduce the speed of a passing fire engine by the change in frequency of its siren,” the researcher continues. “This spectral line is formed in the stratosphere, giving us access to the winds at this altitude.”

What the astronomers discovered was powerful winds in the middle atmosphere of Jupiter in two different locations. One set of winds conformed to expectations, but the other came as a surprise.

Jupiter’s ‘Supersonic Jet’ Winds

Cavalié explains that the team first found a 200 metres per second eastward jet just north of the equator in ‘super-rotation–meaning that the wind rotates faster around the planet than the planet rotates itself. “Winds at such latitudes were expected from models and previous temperature measurements at these low latitudes,” the astronomer adds.

But, not everything observed by the team conformed to expectations.

“Most surprisingly, we identified winds located under the main UV auroral emission near Jupiter’s poles. These winds have velocities of 300 to 400 meters per second,” Cavalié says. “While the equatorial winds were kind of anticipated, the auroral winds and their high speed were absolutely unexpected.”

To put this into perspective, the fastest winds ever recorded on earth reached a speed of just 103 metres per second–measured at the Mount Washington Observatory in 1931. These auroral winds even beat the winds recorded in Jupiter’s Great Red Spot–an ongoing raging storm on the surface of the gas giant–which have been clocked at around 120 metres per second.

The speed of these jets isn’t their only intimidating quality, however. The jets seem to behave like a giant vortex with a diameter around four times that of our entire planet, reaching a height of around 900 kilometres.

“A vortex of this size would be a unique meteorological beast in our Solar System.”

Thibault Cavalié,  Laboratoire d’Astrophysique de Bordeaux, France.

The team’s measurements and stunning discovery, documented in a paper published in the latest edition of Astronomy & Astrophysics, wouldn’t have been possible without a violent incident in Jupiter’s recent history.

Shoemaker-Levy 9 Still has Impact

The impact of Shoemaker-Levy 9 upon the surface of Jupiter was an event–or more precisely a series of events– that had already made history before its effects made this research possible.

The comet broke up in the planet’s atmosphere resulting in a series of impacts that had never been studied prior to 1994, and its somewhat ironic that thanks to this study, Shoemaker-Levy 9 is still having an impact today. The comet left traces of hydrogen cyanide swirling in Jupiter’s atmosphere which the team was able to track.

This image, taken with the MPG/ESO 2.2-metre telescope and the IRAC instrument, shows comet Shoemaker–Levy 9 impacting Jupiter in July 1994. (ESO)

“The team measured the Doppler shift of hydrogen cyanide molecules — tiny changes in the frequency of radiation emitted by the molecules — caused by their motion driven by stratospheric winds on Jupiter,” says Thomas K Greathouse, Senior Research Scientist at Southwest Research Institute (SwRI), responsible for the development of the study and analysis of the observational results. “

“The high spectral and spatial resolution and the exquisite sensitivity of the observations at the wavelengths covered by ALMA allowed us to map such small Doppler shifts caused by the winds in the stratosphere all along the limb of Jupiter.”

Thomas K Greathouse, Senior Research Scientist at Southwest Research Institute (SwRI).

The fact that the team was able to obtain all the measurements they did with just 30 minutes of operating time with ALMA is a striking testament to the power and precision of the 66 antennas that make up the telescope array located in the Atacama Desert of Nothern Chile, currently the most powerful radio telescope on Earth.

“It was the availability of ALMA that made these measurements possible.  Previous radio observatory facilities did not have the combination of spectral and spatial resolution along with the high sensitivity needed to measure the winds as was done in this study,” Greathouse tells ZME Science. “Making further observations using ALMA to capture Jupiter at different orientations will allow us to study these winds in more detail and allow us to look for temporal variability in them as well. 

“Additionally, more extensive measurements will be possible from the JUICE mission and its Submillimetre Wave Instrument slated for launch in 2022.”

The Future of Jupiter Investigations

JUICE or JUpiter ICy moons Explorer is the first large-class mission in the European Space Agency’s (ESA) Cosmic Vision program and will arrive at Jupiter in 2029 when it will begin a three-year mission observing the gas giant in intense detail.

“This is why science is so much fun.  We have worked hard to understand a system–Jupiter’s stratosphere in this case–as best we can, we make our predictions about something–stratospheric wind behaviour–and then go test those predictions. If we are right, fantastic, we move on to the next problem, but if we are wrong we have learned something new and unique and can then continue making further studies to come to a more complete understanding of the system.”

Thomas K Greathouse, Senior Research Scientist at Southwest Research Institute (SwRI).
Amazing image of Jupiter taken in infrared light on the night of 17 August 2008 with the Multi-Conjugate Adaptive Optics Demonstrator (MAD) prototype instrument mounted on ESO’s Very Large Telescope. This false colour photo is the combination of a series of images taken over a time span of about 20 minutes, through three different filters. 9ESO/F. Marchis, M. Wong, E. Marchetti, P. Amico, S. Tordo)

For Cavalié, who has been involved with the measurement of Jupiter’s winds since 2009, the future is bright for such investigations and what they can tell us about the solar system’s largest planet and gas giants in general. “We now want to use ALMA again to characterize the temporal variability of the equatorial winds,” the astronomer says. “It is expected from temperature measurements and models that the direction of the equatorial winds should oscillate from eastward to westward with a period of about 4 years.”

The scientist is also clear, just because he and his colleagues have achieved a first, that doesn’t mean they are prepared to rest on their laurels. There are a lot of exciting developments on the way, and thus a lot of work to be done.

“We also want to observe the auroral winds during a Juno perijove pass to compare our data with observations of the poles by the spacecraft to better understand their origin and what maintains them,” he explains. “In addition, this study is a stepping stone for future investigations to be conducted using the same technique with JUICE and its Submillitre Wave Instrument.”

In addition to these missions, the ESO’s Extremely Large Telescope (ELT)–due to start operations later this decade–will also join investigations of Jupiter and should be capable of providing highly detailed investigations of the gas giant’s atmosphere.

“Jupiter and the giant planets are fascinating worlds. Understanding how these planets formed and how they work is a source of daily motivation, especially when working with world-class observatories like ALMA and participating in space missions to explore Jupiter and its satellites.”

Thibault Cavalié,  Laboratoire d’Astrophysique de Bordeaux, France.

What is Jupiter made of and does it have a solid core?

Jupiter is sometimes called a ‘failed star’ for good reason. The gas giant is the largest planet in the solar system by a large margin and is primarily composed of hydrogen and helium — just like the sun. But despite the fact it’s 318 times bigger than Earth, Jupiter isn’t massive enough for gravity to trigger nuclear fusion, which would have elevated it to stellar status.

Jupiter’s swirling, multicolored clouds wind through this color-enhanced close-up taken by Juno’s visible-light camera in 2018. Credit: f NASA/JPL-CALTECH/SwRI/MSSS.

The fifth planet from the sun has an atmosphere composed of about 90% hydrogen and about 10% helium, with trace amounts of other gases. These include water vapor, methane, hydrogen sulfide, neon, oxygen, phosphine, carbon, ethane, sulfur, and ammonia crystals, according to spectral analyses of the planet.

The atmosphere is not uniform with the gases being piled on top of one another, forming multiple layers extending downward, including a layer of supercritical hydrogen (the point where distinct liquid and gas phases do not exist).

These layers aren’t necessarily linked to Jupiter’s famous stripes. These are actually the result of a combination of a fast rotation of the planet and dramatic differences in temperature in various regions. Earth rotates once in 24 hours, whereas Jupiter rotates once in about 9.5 hours. However, the surface of Earth at the equator is rotating at about 1000 miles per hour, while Jupiter’s equatorial cloud-tops are moving nearly 28,000 miles per hour. Jupiter’s equator is also more intensely heated than at the poles. The physics responsible for Jupiter’s stripes is actually quite similar to that responsible for trade winds near the equator and jet streams near the poles on Earth.

But unlike Earth, Jupiter doesn’t have a solid surface, so a visitor traveling through the Jovian atmosphere in a spacecraft would simply plow through like a knife through the mist. However, for practical purposes, scientists consider Jupiter’s surface the geodesic line where the atmospheric pressure is equal to that of Earth at sea level — at this point, gravity is 2.5 times more powerful than on Earth.

However, this hypothetical spacecraft wouldn’t just end up on the other side of the planet if it kept zipping through in a straight line — at some point, it would crash into Jupiter’s core, estimated to be about 35,000 degrees Celsius (63,000 degrees Fahrenheit).

Does Jupiter have a solid core?

Scientists still aren’t sure what this core looks like since the dense and swirling clouds obstruct observations. But there are reasons to believe Jupiter has a dense rocky center enveloped in a layer of metallic hydrogen (a phase of hydrogen in which it behaves like an electrical conductor), with another layer of molecular hydrogen (regular H2, dihydrogen gas) on top.

The presence of a rocky core is also supported by models of planetary formation which show that a rocky core, or at the very least an icy one, would have been necessary at some point in the gas giant’s history.

According to a 1997 study, which performed gravitational measurements, Jupiter’s core could have a mass of 12 to 45 times the mass of planet Earth — that’s 4% to 14% of Jupiter’s total mass.

Another school of thought concerning Jupiter’s core suggests that the gas giant lacks a rocky core. Instead, when the planet formed billions of years ago, a pocket of gas simply collapsed in on itself, creating a more-or-less pure hydrogen-helium world.

But this latter hypothesis has since been dispelled by the Juno mission. Launched in August 2011, the spacecraft named after Jupiter’s wife in Roman mythology has revealed numerous secrets about Jupiter.

By measuring how the spacecraft’s velocity was ramped up or slowed down by the planet’s gravitational field, scientists could deduce how mass is distributed in Jupiter’s depths. Although there’s no way to peer through Jupiter’s swirling dense clouds, this clever method confirmed that Jupiter does indeed have a core, scientists wrote in the journal Nature. What’s more, rather than being a compact ball, the analysis showed that the core is more like a fuzzy sphere spread across nearly half of Jupiter’s diameter.

Scientists don’t actually know why Jupiter has such an atypical core, but whatever the explanation may be, it’s telling of how the planet formed. One possible explanation is that early Jupiter was stirred up by the impact with another huge proto-planetary body. Another explanation would be that Jupiter changed orbit and added more planetesimals early in its history.

Nevertheless, this insight showed that we still don’t know much about giant gas planets. Besides overturning assumptions about Jupiter’s core, the Juno mission also showed that the strange clusters of cyclones raging around the planet’s north and south poles are more chaotic than previously thought. Another surprise was Jupiter’s magnetic field, which turned out to be twice as strong than scientists assumed.

As Juno continues its mission exploring Jupiter and its moons, NASA scientists hope to uncover strange new things about Jupiter.

Twinkle, twinkle, little … moon? Jupiter’s icy moon Europa glows in the dark, researchers find

Europa, the frozen but ocean-filled moon that orbits Jupiter is bombarded by a relentless flux of radiation. Day in and day out, Jupiter flings electrons and other particles towards it. These particles hit the ice and salt-rich surface of Europa, creating a soup of complex interactions that produce something otherworldly: they make Europa glow in the dark.

This artistic illustration of Jupiter’s moon Europa shows how the icy surface may glow on the side facing away from the Sun (like the Earth’s moon, Europa is tidally locked so one side always faces Jupiter and one side always faces away). Variations in the glow and the color of the glow itself could reveal information about the composition of ice on Europa’s surface. Credit: NASA/JPL-Caltech

A song of ice and radiation

Cold Europa is already a hotspot of interest for astronomers. Although it is a frozen desert on the surface, astronomers believe it harbors liquid water beneath its icy crust, and based on what we know about its chemical make-up, it seems like a promising candidate for hosting life in this subsurface ocean.

But while the inside of the planed may be teeming with life (it’s probably not teeming, but you know), the surface is interesting in its own right. NASA astronomer Murthy Gudipati and colleagues recreated some of the interactions on Europa’s surface in the lab, exposing salted ice to energetic electrons as they would expect from Jupiter. They found that these interactions trigger a process called electron-stimulated luminescence. Simply put, it glows in the dark.

It’s an unusual process. You may be tricked into thinking it’s common for moons to glow by looking at our very own moon, bright on the night sky. But our moon isn’t glowing, it’s merely reflecting light from the Sun. Meanwhile, Europa truly produces its own light, even on the side that’s turned away from the Sun.

The surface of Europa is covered in cracked and ridged ice. Imge credits: NASA/JPL

This is more than just a cool factoid that researchers have found about Europa. The work presented here is important for understanding Europa’s surface chemical composition and mineralogy, which in turn affect its habitability.

“We were able to predict that this nightside ice glow could provide additional information on Europa’s surface composition. How that composition varies could give us clues about whether Europa harbors conditions suitable for life,” said JPL’s Murthy Gudipati, lead author of the work published Nov. 9 in Nature Astronomy.

“If Europa weren’t under this radiation, it would look the way our moon looks to us—dark on the shadowed side,” Gudipati adds. “But because it’s bombarded by the radiation from Jupiter, it glows in the dark.”

What science is all about

The salty compounds react differently to the radiation and emit their own unique glimmer. By analyzing these glimmers at different wavelengths, astronomers can connect them to their “signatures” and assess the chemical make-up of the moon. This came as a bit of a surprise: researchers didn’t expect to see variations in the glow itself tied to different ice compositions. It was, the researchers call it, serendipity.

“Seeing the sodium chloride brine with a significantly lower level of glow was the ‘aha’ moment that changed the course of the research,” said Fred Bateman, co-author of the paper. He helped conduct the experiment and delivered radiation beams to the ice samples at the Medical Industrial Radiation Facility at the National Institute of Standards and Technology in Maryland.

The proposed robot lander on the surface of Europa (artistic depiction) during the Clipper mission. Image credits: NASA/JPL.

So far, the researchers haven’t made any new discoveries about the chemistry of Europa. We’ll have to wait for NASA’s upcoming Europa Clipper mission, which will observe the moon’s surface over multiple flybys. These flybys (and the planned robot lander) could map Europa’s chemistry and gain insights about the sub-surface ocean (especially its salinity).

It’s uncommon for a lab experiment to be help a space mission know what to prepare for, but this is exactly what science is all about, says Gudipati.

“It’s not often that you’re in a lab and say, ‘We might find this when we get there,'” Gudipati said. “Usually it’s the other way around—you go there and find something and try to explain it in the lab. But our prediction goes back to a simple observation, and that’s what science is about.”

Europa Clipper is set to launch in the mid-2020s and it’s set to be one of the most exciting missions of the decade as it will investigate a part of the solar system that’s promising in regards to extraterrestrial life. Researchers are now reviewing the findings to see how Clipper’s scientific toolkit could detect variations in the moon’s glow.

Journal Reference: Laboratory predictions for the night-side surface ice glow of Europa, Nature Astronomy (2020). DOI: 10.1038/s41550-020-01248-1 , www.nature.com/articles/s41550-020-01248-1

Venus might be a hellscape today because of Jupiter

While Venus is boiling-hot today, this wasn’t always the case. And the culprit, new research suggests, could be our largest neighbor.

Image credits Pablo Carlos Budassi via Wikimedia.

Jupiter, the colossus of our solar system, likely altered the orbit of Venus in the past, condemning it to a state of lifelessness. The findings come from a new study that aimed to understand why Venus’ orbit around the sun is so circular.

Big players

“One of the interesting things about the Venus of today is that its orbit is almost perfectly circular,” said UCR astrobiologist Stephen Kane, who led the study.

“With this project, I wanted to explore whether the orbit has always been circular and if not, what are the implications of that?”

Jupiter is by far the largest planet in our vicinity, with a mass over two-and-a-half times greater than that of all other planets in the solar system combined. As such, it can wield quite a lot of (gravitational) influence upon them.

During its early days, Jupiter moved towards the sun and then away from it again. This isn’t really a very peculiar case — observations from other systems show that giant planets follow such orbits pretty often during their formation.

In our corner of space, Jupiter’s motion affected the orbit of Venus. This put it on the path to becoming the planet it is today. Kane says that while it’s very likely that Venus lost some of its water due to other reasons, the passing of Jupiter irrevocably changed its climate and drained its reserves of liquid water. Researchers mostly consider any planet lacking liquid water to be incapable of spawning life, or at least, life as we know it.

“As Jupiter migrated, Venus would have gone through dramatic changes in climate, heating up then cooling off and increasingly losing its water into the atmosphere,” Kane said.

Kane created a model of the solar system during the early days of planetary formation, calculating where each of them was and how their gravitational pull influenced one another. This model showed that Venus used to have a much less circular (more ‘eccentric’) orbit than today. A planet’s eccentricity is denoted by a number between 0 and 1, with the first meaning perfectly circular and 1 meaning completely linear. Kane explains that a planet with an eccentricity of 1 would “simply launch into space”.

Currently, the orbit of Venus has an eccentricity of 0.006, making it the most circular in the whole Solar System. However, the model holds that this value used to be 0.3 before Jupiter came around. Kane says Venus had a much higher probability of being habitable at that time. The recent discovery of phosphine in the atmosphere of Venus — a gas that is typically produced by microbes — could be the signature of “the last surviving species on a planet that went through a dramatic change in its environment.”

Still, any surviving microbes would have needed to live in the clouds of sulfuric acid that drape the planet for over a billion years without liquid water.

“There are probably a lot of other processes that could produce the gas that haven’t yet been explored,” Kane said.

“I focus on the differences between Venus and Earth, and what went wrong for Venus, so we can gain insight into how the Earth is habitable, and what we can do to shepherd this planet as best we can.”

The findings “Could the Migration of Jupiter Have Accelerated the Atmospheric Evolution of Venus?” have been published in The Planetary Science Journal.

Pastel Jupiter showcases violent storms in unprecedented details

In the past few years, we’ve been spoiled with some awesome Jupiter photos, and this one is no exception. This latest, pastel-colored image is so detailed it can serve as a weather report of the planet’s monstrous atmosphere.

An image of Jupiter taken by NASA’s Hubble Space Telescope in ultraviolet, visible, and near-infrared light on Aug. 25, 2020, is giving researchers an entirely new view of the giant planet. Image credits: NASA, ESA, STScI, A. Simon (Goddard Space Flight Center), M.H. Wong (University of California, Berkeley), and the OPAL team.

Jupiter’s Great Red Spot takes all the spotlight when it comes to jovian storms, but while it is undoubtedly a mammoth storm, it’s far from the only one. For instance, opposite to the Great Red Spot (in the top-left part of the picture), there’s a remarkable new storm brewing.

The white stretched-out storm is already traveling around the planet at 350 miles per hour (560 kilometers per hour), despite only emerging on August 18, 2020. It’s also accompanied by two other, smaller storms at about the same latitude. According to a NASA statement, this new Hubble image “shows that Jupiter is clearing out its higher altitude white clouds, especially along the planet’s equator, where an orangish hydrocarbon smog wraps around it.”

Another notable storm is the so-called Red Spot Jr., a storm that appears just below the Great Red Spot in this image. For years, Red Spot Jr. has been fading to a shade of white after appearing red in 2006, but now it seems to be turning towards red once again.

As for the Red Spot itself, it’s still shrinking, for reasons that are not well understood. However, it still measures 9,800 miles across, which makes it big enough to swallow the Earth whole.

No matter how many times you look at it, Jupiter is still stunning. Image credits: NASA, ESA, STScI, A. Simon (Goddard Space Flight Center), M.H. Wong (University of California, Berkeley), and the OPAL team.

The icy satellite Europe is also visible to the left of Jupiter. Europe has drawn astronomers’ attention as one of the prime candidates for extraterrestrial life in our solar system. Not only does Europe have a liquid ocean under its frozen surface, but it also seems to have salt and hydrothermal vents, essentially supplying all the necessary ingredients for life as we know it.

NASA is already preparing a mission to study Europa on-site, with the Europa Clipper spacecraft set for launch sometime between 2023 and 2025. Europa Clipper will conduct detailed reconnaissance of Jupiter’s moon, looking for signs of life and sending a lander to the surface of the satellite.

11 mind-blowing facts about Jupiter

Jupiter is named after the Roman king of the gods for good reason. It’s the largest planet in the solar system and has more moons than any other planet. But that’s not all. Read on for more facts about one of the most amazing planets in the solar system.

1. Jupiter is the king of planets by mass

Credit: Pixabay.

Everyone’s learned at school that Jupiter is the largest planet in the solar system. However, this is a bit of an understatement. Jupiter is by far the most massive cosmic body in the solar system, being 2.5 times more massive than all other planets combined. It is nearly 318 times more massive than Earth and it would take 11 Earths lined up next to each to match Jupiter’s diameter.

2. Its Great Red Spot is actually a planetary-sized storm that has been raging on for centuries

Image of Jupiter’s Great Red Spot processed using low resolution (wide angle) orange, green, and blue filtered images overlaying high resolution (narrow angle) orange images taken by Voyager 2 on July 8 1979. Credit: NASA/JPL-Caltech/Kevin M. Gill.

In 1665, famed Italian astronomer Giovanni Cassini observed a huge blemish south of Jupiter’s equator. This ‘Great Red Spot’, as it’s still called today, has been the subject of contention among astronomers for centuries. Some have proposed that the feature, which is large enough to contain 2-3 planets the size of Earth’s diameter, is a huge storm. This is indeed the case, NASA scientists found after the Voyager 1 mission completed a flyby of the planet in 1979.

Scientists confirmed that the Great Red Spot is an extremely persistent anticyclonic storm, fueled by Jupiter’s turbulent and fast-moving atmosphere.

The red spot spins anticlockwise and takes six Earth days to rotate completely. However, it remains a mystery why this stormy region is red. One possible explanation is the presence of red organic compounds.

The Great Red Spot might disappear in the next few centuries, though. During Cassini’s observations, the size of the spot is estimated to have been 40,000 km, whereas today it is about half as large. However, astronomers are fairly confident a new giant red spot will appear somewhere else on Jupiter’s surface, due to the planet’s atmospheric dynamics.

3. The first astronomers to track Jupiter were Babylonians

It’s no secret that the ancient Babylonians were skilled mathematicians. For instance, they understood the Pythagorean theorem nearly 4,000 years ago, or more than a millennium before Pythagoras himself was born.

Their mathematical prowess naturally extended to astronomy, regularly employing arithmetic to catalog the movements of celestial bodies and improve their astronomical predictions.

Mathieu Ossendrijver of Germany’s Humboldt University of Berlin spent no less than 13 years studying 2,400-year-old tablets that contained what he described as a “small bunch of four weird trapezoid computations.” He later found that the trapezoids encoded aspects of Jupiter’s motion, including its appearances on the horizon.

4. Jupiter has the shortest day of all planets, despite its hefty size

For all its monstrous size and mass, you’d think Jupiter would be slow to rotate around its axis. However, it’s the fastest spinning planet in the solar system, with a rotational velocity of 45,300 km/h.

As such, a day on Jupiter only lasts 9 hours and 55 minutes. A year, however, is much longer — Jupiter orbits the sun every 11.8 Earth years.

What’s more, due to this rapid rotation, the planet has an oblate shape with flattened poles and a bulging equator. Its powerful rotation is also responsible for the next point.

5. Jupiter has the strongest magnetic field of any planet in the solar system

 Schematic of the Jovian magnetosphere showing the Io Plasma Torus (in red), the Neutral Sodium immediately surrounding Io (in yellow), the Io flux tube (in green), and magnetic field lines (in blue). Credit: Wikimedia Commons, John Spencer.

Like Earth, Jupiter’s core is made of active, swirling molten material whose motion generates a magnetic field — and a very powerful one to boot. According to measurements performed by NASA, Jupiter’s magnetic field is at least 14 times stronger than Earth’s, making it the most powerful in the solar system.

6. Jupiter has a thin ring system

 A schematic of Jupiter’s ring system. Credit: Wikimedia Commons.

This wouldn’t be a list of facts about Jupiter without mentioning its rings. Unlike Saturn’s more iconic rings, Jupiter’s are very faint and made of dust rather than ice.

For centuries, these rings were too faint for astronomers to notice. Imagine everyone’s surprise when NASA’s Voyager 1 spacecraft beamed back images of Jupiter’s rings in 1979. The three-ring system begins some 92,000 kilometers above Jupiter’s cloud tops and stretches out to more than 225,000 km from the planet. They are between 2,000 to 12,500 kilometers thick.

7. Jupiter has 79 moons and counting

Jupiter’s moon Ganymede in the foreground. Credit: Pixy.

Until recently, Jupiter was widely regarded as the planet of the solar system with the most natural satellites. That’s until 2019, when astronomers affiliated with the Carnegie Institution for Science in Washington DC raised the total number of moons around Saturn to 82, beating Jupiter’s 79.

Almost all of Jupiter’s moons are tiny, with a diameter of less than 10 kilometers. This is also one of the reasons why astronomers are constantly finding new moons around both Jupiter and Saturn.

Jupiter does have some moons that stand out more. These four major moons are collectively known as Galilean Moons. They are Io, Europa, Ganymede, and Callisto. Ganymede, with a diameter of 5,262 km, is actually the largest moon in the solar system. And, who knows, perhaps Jupiter might regain its title as the most moon-populated planet as scientists believe it may have as many as 200 natural satellites orbiting it.

8. And some of these moons may actually be capable of harboring life

The Voyager and Galileo missions that sent spacecraft to Jupiter and its moons found that Europa, one of the biggest moons in the solar system, has a subsurface liquid ocean covered in thick ice. Now, scientists believe that Europa may actually be capable of harboring life since it meets three essential conditions: biochemically useful molecules, a source of energy, and a liquid solvent (water) in which dissolved substances can chemically react with each other.

But to ultimately find life on Europa, we have to get beneath the ice by one day putting a lander on the surface, potentially carrying a submarine. 

9. Jupiter has the brightest auroras in the solar system

Artistic impression of an aurora on Jupiter.

From time to time, people are treated to nature’s dazzling fireworks show; the Aurora borealis, also known as the Northern Lights. This eye candy phenomenon is caused by the collision of energetic charged particles with atoms in the high altitude atmosphere — and it’s not reserved to Earth. Auroras have also been spotted on Mars, Uranus, and, yes, Jupiter.

Jupiter actually experiences the most intense auroras in the solar system, being hundreds of times brighter than on Earth. Just like on Earth, auroras on Jupiter are caused by solar storms. However, Jupiter has an additional source for its auroras: charged particles thrown into space by its orbiting moon Io, which is famous for its many large volcanoes.

10. Jupiter is a ‘failed star’

The gas giant is virtually made of 90% hydrogen and 10% helium, that’s mighty close to the sun’s composition. In fact, some consider Jupiter to be a ‘failed star’. Jupiter is already a big boy, but if it were roughly 80 times more massive than it is, it could have collapsed under its own gravity to form a star.

11. Jupiter is the solar system’s asteroid vacuum cleaner

Due to its sheer mass and proximity to the Kuiper belt — a huge region of space beyond Neptune packed with asteroids and dwarf planets — Jupiter attracts a lot of visitors. Astronomers believe Jupiter experiences at least 200 times more meteorite impacts than Earth. So, kudos to Jupiter for clearing the solar system of potentially hazardous asteroids that might have come dangerously close to Earth.

Did we miss something? Share your favorite Jovian factoids in the comment section.


NASA captures the first images of Ganymede’s icy north pole

Extraordinary views of the largest moon in the solar system, Ganymede, were captured by NASA’s Juno Jupiter probe. This data provides the first infrared mapping of the massive moon’s northern frontier and could help to understand the evolution of the Jovian moons.

Credit NASA

The moon has long attracted astronomers since Galileo discovered it in 1610. While he didn’t have many of the tools needed to examine it at his disposal, now NASA does. The Juno Jupiter probe captured infrared imagery, using the Jovian Infrared Auroral Mapper (JIRAM) instrument.

While JIRAM was initially designed to capture the infrared light emerging from deep inside Jupiter, thus probing its ‘weather layer’, it can also be used to study the moons. This includes Europa, Ganymede, and Callisto, collectively known as the Galilean moons for their discoverer.

“The JIRAM data shows the ice at and surrounding Ganymede’s north pole has been modified by the precipitation of plasma,” said Alessandro Mura, a Juno co-investigator, in a press release. “It is a phenomenon that we have been able to learn about for the first time with Juno because we are able to see the north pole in its entirety.”

Ganymede, which is larger than Mercury and Pluto, consists mainly of water ice and is the only moon in the solar system with its own magnetic field. On Earth, the magnetic field allows plasma to enter the atmosphere and create auroras. But Ganymede has no atmosphere so its surface receives plasma from Jupiter’s magnetosphere. The plasma stops the ice in Ganymede’s poles from turning into the structures we see on Earth.

On Earth, water forms a crystalline structure after it freezes, with layers upon layers of water molecules forming a lattice of hexagonal rings. But this doesn’t happen on Ganymede, where the ice has an amorphous form.

Analyzing and understanding these structures will help to understand the formation of Jupiter’s moons and the forces that shaped them. The European Space Agency also plans to explore the moon with the spacecraft JUICE (Jupiter Icy Mons Explore) which will be launched in 2022.

The north pole of Ganymede can be seen in center of this annotated image taken by the JIRAM infrared imager aboard NASA’s Juno spacecraft. Credit NASA

The European spacecraft will reach Jupiter by 2029 and should start performing close-up science at Ganymede around 2032. NASA’s plans are also set to continue, exploring another Jupiter moon around the same time with the assistance of Europa Clipper.

The Juno spacecraft entered the orbit of Jupiter 2016 with the main goal of revealing the story of Jupiter’s formation and evolution. Juno will use diverse technologies on a spinning spacecraft placed in an elliptical polar orbit to analyze Jupiter’s gravity and magnetic fields, atmospheric dynamics and composition, as well as its evolution.

Jovian planets — the giants of solar systems

The gas planets, the giants of the solar system, the jovian planets — call them what you will, these planets have fascinated mankind for centuries, and they’re still one of the more intriguing astronomical bodies out there.

Jovian literally means “Jupiter-like”, from “Jove” — another name for the Roman god Jupiter (called Zeus by the Greeks). They are primarily composed of gas or ice and are much larger than the Earth. They’re also much easier to detect than other planets — largely because they’re so big.

The name-giver of all Jovian planets: Jupiter. Jupiter is 318 times as massive as Earth, and it is 2.5 times larger than all the planets in the solar system combined. Image credits: NASA.

You can’t walk on a jovian planet

Jovian planets are comprised of fluid (gases or ices) rather than rock or other solid matter. Although giant rocky planets can exist, these are thought to be much rarer than gas or ice giants.

Jupiter is made up almost entirely of hydrogen and helium — the same elements found in the Sun, though at different temperatures and pressures. Here on Earth, hydrogen and helium are gases, but under the huge temperatures and pressures of Jupiter, hydrogen can be a liquid or even a kind of metal. We’re not entirely sure what lies at the center of Jupiter, but researchers believe that most likely, the core is similar to a thick, boiling-hot soup with a temperature of about 55,000 Fahrenheit (30,000 Celsius).

Saturn has a similar structure, with layers of metallic hydrogen, liquid hydrogen, and gaseous hydrogen, covered by a layer of visible clouds. Unlike Jupiter and Saturn, Uranus and Neptune have cores of rock and metal and different chemical compositions.

A potential internal structure of the jovian planets. It’s not clear if the core consists of rock, but it must be something very dense and hot. Image credits: University of Virginia.

We’re not sure exactly what the surface of jovian planets is like, but based on all we know, it’s not something you can walk on. Jovian planets tend to have very thick clouds (the clouds on Jupiter, for instance, are 30 miles or 50 km thick). After that, there’s gaseous hydrogen and helium, then more and more condensed gas, until you ultimately end up in liquid, metallic hydrogen. Saturn has a similar structure, though it is far less massive than Jupiter.

You might even have trouble realizing where the atmosphere ends and where the “planet” begins.

Methane clouds on Neptune. Image credits: NASA / JPL.

Uranus and Neptune, much smaller than both Jupiter and Saturn, have gaseous hydrogen surrounding a mantle of ice and a rocky core.

Jovian planets also have atmospheres with bands of circulating material. These bands typically encircle the planet parallel to the equator, with lighter bands lying at higher altitudes and being areas of higher pressure, and darker bands being lower in the atmosphere as low-pressure regions. This atmospheric circulation is similar only in principle to that on Earth, it has a very different structure.

Atmospheric bands on Jupiter. Image credits: NASA/JPL.

There are also other, smaller visible structures. The most famous of these is Jupiter’s Great Red Spot, which is essentially a giant storm that has been active for centuries. Saturn’s hexagon is another very well-known feature — both of these are much larger than the Earth itself.

These spinning balls of gas and liquids are truly impressive, and we’re still learning new things about them.

Jovian planets in our solar system

While still far smaller than the sun, jovian planets are by far the largest planets in our solar system. Image credits: NASA / University of Virginia.

Not all gas planets are alike. In fact, the reason why some astronomers prefer the term jovian planets to gas giants is that not all jovian planets are made of gas.

For instance, just Jupiter and Saturn are true gas giants, whereas Uranus and Neptune are ice giants. However, even this is a bit misleading: at the temperature and pressures on these planets, distinct gas and liquid phases cease to exist. Even so, the chemistry of the two groups is different: hydrogen and helium dominate Jupiter and Saturn, whereas, in the case of Uranus and Neptune, it’s water, methane, and ammonia. The two latter planets are thought to have a slushie-like mantle that spans over half of the planet diameter.

Image credits: NASA.

All four of these planets have large systems of satellites, and these satellites can be very interesting in their own right (we’ll get to that in a minute — there’s a good chance that life may be hiding in the jovian satellites). Saturn, for instance, has 82 designated satellites, and countless undesignated moonlets. Despite being larger, Jupiter “only” has 79 known satellites. Uranus has 27 and Neptune has 14.

All these four planets also have rings, though Saturn’s are by far the most pronounced.

Artist’s impression of the Voyager probe with the Jovian planets and some of their satellites. If you look closely, you can see Neptune’s rings. Image credits: Don Davis.

Much of what we know about gas and ice giants in general, we extrapolate from what we see in our own solar system. This being said, astronomers are aware that jovian planets can be very different and have a much greater variety than we see in our solar system.

Extrasolar Jovian planets

Roughly speaking, jovian planets can be split into 4 categories:

  • gas giants (like Jupiter and Saturn) — mostly consisting of hydrogen and helium, and only 3-13% heavier elements;
  • ice giants (like Neptune and Uranus) — a hydrogen-rich atmosphere covering an icy layer of water;
  • massive solid planets (somewhat similar to the Earth, but huge) — tangible evidence for this type of planet only emerged in 2014, and these planets are still poorly understood. Astronomers suspect that solid planets up to thousands of Earth masses may be able to form, but only around massive stars;
  • super puffs — planets comparable in size with Jupiter, but in mass with the Earth. These planets are super rarefied, and were only discovered in the past decade; the most extreme examples known are the three planets around Kepler-51.
Artistic rendering of Gliese 3470 b — a rare “superpuff”. The two are believed to be comparable in mass. Image credits: NASA.

Based on what we’ve seen so far, jovian planets seem pretty common across our galaxy. However, we’ve only started discovering exoplanets very recently, and it’s hard to say whether the planets we’ve found so far are representative of the larger picture.

However, based on the fact that researchers have discovered far more Neptune-sized planets than Jupiter-sized planets (although the latter are easier to discover), it’s pretty safe to say that it’s the Neptune-sized planets that are more common.

Image credits: NASA.

A particularly interesting class of jovian planets is the so-called Hot Jupiters.

Hot Jupiters are the easiest planets to detect. As the name implies, they are Jupiter-sized planets, but they lie very close to their stars and have a rapid orbital period that produces effects that are more easily detected. For instance, one such planet revolved around its star in only 18 hours, making for one very short year. Another freakish example of a Hot Jupiter is believed to have surface temperatures of 4,300°C (7,800°F) — which is hotter than some stars we know.

Extrasolar planets, and Hot Jupiters in particular, can shed a lot of light on the evolution of solar systems. It is believed that these planets form in the outer parts of solar systems (like Jupiter), but they slowly migrate towards the star, drawn by gravitational attraction. As they do so, they could wreak havoc on the entire solar system, much like a big billiards ball.

Artist’s impression of a Hot Jupiter. Image credits: ESO/L. Calçada.

Some jovian planets get so large that they blur the line between a planet and a brown dwarf. Brown dwarfs are neither truly stars nor planets. As a rule of thumb, jovian planets are only “planets” until they are 15 times the mass of Jupiter — after that, they “become” brown dwarfs.

Because of the limited techniques currently available to detect and study exoplanets, there are still many things we don’t know about exoplanets, even those as big as Jupiter. We tend to associate these planets by size with the ones in our own solar system, piecing together other available information (which is scarce). As our telescopes, equipment, and theoretical models become better, we will no doubt better our understanding of jovian planets, and exoplanets in general.

This image shows an artist’s impression of the ten hot Jupiter exoplanets studied by David Sing and his colleagues. From top left to to lower left these planets are WASP-12b, WASP-6b, WASP-31b, WASP-39b, HD 189733b, HAT-P-12b, WASP-17b, WASP-19b, HAT-P-1b and HD 209458b.

Life around Jovian planets

Jovian planets are not exactly life-friendly — at least not directly. A giant, spinning, mass of fluid you can’t even stand on, either very hot or very cold, doesn’t sound very attractive to life forms. But jovian satellites are a different story. In fact, astronomers are starting to believe that the satellites of Jupiter and Saturn may be the best places to look for extraterrestrial life in our solar system.

Both Jupiter and Saturn lie rather far from the Sun. They are cold, frigid places, as are their satellites — at least on the surface.

Jupiter’s icy moon, Europa. Image credits: NASA.

Researchers now believe that some of the icy satellites of Jupiter and Saturn (especially Europa and Enceladus) could host life under their frozen surfaces.

Although the surface temperatures are extremely low on these satellites, astronomers have some clues that both satellites may harbor oceans of liquid water beneath the frozen surface. Basically, the huge gravitational effect from their host planets causes friction and shear in the ice, which produces sufficient heat to melt the ice. This is called tidal heating. Geothermal and geological activity may also contribute to this effect, creating a liquid, salty water beneath the ice — and while this has not yet been confirmed, these could be suitable conditions for life to emerge.

Enceladus is believed to harbor a liquid ocean in its subsurface. Image credits: NASA / JPL.

In addition to Europa and Enceladus, several other jovian satellites could harbor life (with various degrees of likelihood): Callisto, Ganymede, Io, Triton, Dione, and even Pluto’s moon Charon could all have a liquid ocean compatible with life. NASA’s Clipper mission is set for launch in 2024, with the goal of exploring Europa’s potential habitability. Some scientists believe there are as many habitable exomoons as there are habitable exoplanets.

Jovian planets seem to play a key role in the structure of solar systems. Whether their satellites can hold life or not, they are an extremely important puzzle piece in our understanding of how solar systems form, evolve, and how the Earth fits in this grand cosmic puzzle.

Jupiter will be very bright and visible tonight, as it comes closest to Earth

The largest planet in our Solar System will be shining bright tonight and in the early hours of Tuesday morning.

Jupiter, seen by the Juno spacecraft.
Image via Wikimedia.

According to NASA, the orange giant will be in ‘opposition’ to Earth — at its closest point to our home in its orbit. Its size and proximity should make it very easy to spot during this time, with only the Moon and Venus likely to out-do it in terms of shine.

The best time to spot it should be between midnight and 2 in the morning. Light-drenched environments such as big cities aren’t going to be the best viewing spots (although Jupiter, which will outshine stars, should still be visible from here).

Your local weather conditions will obviously also impact visibility. Most of the US is forecasted to see clear night skies on Monday. The forecast for Europe is a bit more uncertain, with central and Eastern Europe likely to see rain.

“When a planet is at opposition, it is the best time to look for it in the night sky. This is the point in its orbit when it’s closest to the Earth, making it appear brighter than other times of the year,” AccuWeather explains.

The term ‘opposition’ refers to two celestial bodies being on opposite sides of a third one, usually the star they orbit (in this case, the Sun).

If you like star (planet?) gazing, this isn’t the only treat you’re getting this month. Jupiter, the yellow slightly-smaller giant behind Jupiter, will also reach opposition on July 20. Comet Neowise, discovered in late March, will be putting on “Earth’s greatest cometary show in 13 years”. It will become visible starting with 12-13 July and be most visible on the 23rd, according to Forbes.

Neowise is brighter than Halley’s Comet was in 1986 at the moment, and will only get brighter as it nears the Sun.

So make sure to keep your eyes on the skies this month, and not miss the show that nature is putting on.

Amateur astronomer finds and christens Clyde’s Spot — a new storm on Jupiter

Although NASA has sent a craft to Jupiter’s orbit — the Juno probe — a newly-named region of the planet was recently spotted by an amateur astronomer.

Clyde’s Spot, seen here in the center as a white maelstrom, just below and to the right of the Great Red Spot. Image processed by Kevin Gill using JunoCam data.
Image credits NASA/JPL-Caltech/SwRI/MSSS / Kevin M. Gill.

The structure, a swirl not far from the planet’s infamous Great Red Spot, has been christened the somewhat anticlimactic ‘Clyde’s Spot‘. At the time it was observed, Juno was flying between 28,000 miles and 59,000 miles (45,000 to 95,000 kilometers) above Jupiter’s southern cloud tops.

Long-distance spotting

“The feature is a plume of cloud material erupting above the upper cloud layers of the Jovian atmosphere,” according to a NASA description of the new imagery. “These powerful convective ‘outbreaks’ occasionally erupt in this latitude band, known as the South Temperate Belt.”

After it was spotted by Clyde Foster from Centurion, South Africa on May 31, Juno moved in to take some better-quality pictures of the structure on June 2 — which is, as far as we know, a storm.

It rages in swirls not far off from Jupiter’s centuries-old Great Red Spot. Unlike the iconic storm, however, Clyde’s Spot is young, having just popped up. It’s not the first time such a storm appeared out of the brown and orange clouds: Juno captured another similar system at this latitude back in February of 2018.

An image of Jupiter taken by Clyde Foster. The new storm sits just below and to the right of the Great Red Spot.
Image credits Clyde Foster.

Juno orbits Jupiter on an elliptical orbit, so it does most of its data-gathering every 53.3 (Earth) days as it comes closest to the gas giant. Its latest fly-by luckily placed it at the ideal angle to capture Clyde’s Spot on its JunoCam. NASA makes JunoCam images available to the public, and citizen scientist Kevin Gill processed five of its images into a composite view of Clyde’s Spot. Gill is responsible for many of the striking NASA images you’ve seen online.

Both his work and that of Foster shows that there’s enough space in space exploration for everybody down here on terra firma — and an amazing wealth of beauty and science to share with us.

Astronomers find the stripped core of a gas giant for the first time

Illustration of the exoplanet core orbiting extremly close to its parent star. Credit: University of Warwick.

Gas giants like Jupiter and Saturn are mind-bogglingly huge, but that’s because their atmospheres are exceptionally thick. In fact, to this day, scientists aren’t sure what lies beneath their atmospheric shell of hydrogen and nitrogen. But a distant ‘failed’ gas giant may offer some clues.

A team of astronomers led by researchers at Warwick University has identified the first core of a gaseous world, offering an unprecedented glimpse into what such solid core might look like.

The researchers were initially running a survey of exposed planetary cores from data gathered by the TESS space telescope. That’s when they came across TOI 849 b, a large object circling a sun-like star about 730 light-years away from Earth.

Follow-up observations with the HARPS spectrograph in Chile confirmed that the object was truly massive. Although the exoplanet is three-and-a-half times larger than Earth, it’s around 39 times more massive.

Considering its size and density, the only viable explanation is that TOI 849 b is actually the core of a former gas giant — now, just a rocky giant.

It might not be a pretty sight either. The core is estimated to complete a full orbit around its parent star every 18 hours, which means it’s mighty close to solar radiation. Its surface temperature is believed to be around 1,527 degrees Celsius as a result.

Although it’s not clear how TOI 849 b lost its gaseous envelope, the astronomers have proposed two plausible scenarios. The most likely explanation is that extremely powerful tidal forces generated by the close orbit ripped apart the gas atmosphere. Alternatively, the former gas giant may have collided with another planet.

The second possibility is that TOI 849 b never had the chance to complete its gaseous atmosphere. This may have occurred due to a gap in the disc of gas and dust from which it was forged. However, the researchers are less inclined to lean on this hypothesis.

“I think one of the biggest clues is that we found the planet inside the ‘Hot Neptunian desert’, which is this region of parameter space where we don’t typically find planets,” lead author David Armstrong told BBC News.

“That hints that it has gone through quite an unusual evolution. To me that hints that it is more likely that it did lose its atmosphere… but we’ll need some more observations to be sure.”

Although TOI 849 b is hundreds of light-years away, the rocky core might provide invaluable insights about planets closer to home.

Initially, scientists believed that Jupiter would have a solid core covered in a ‘crust’ of liquid hydrogen that is bombarded by helium rain. However, relatively recent observations performed by the Juno spacecraft showed that the gravitational measurements don’t add up, pointing instead towards “a core that is not solid like Earth’s, but “fuzzy” and dilutely mingled with the overlying metallic hydrogen layer,” New Scientist reports.

But, the jury is still out and there are many unknowns regarding the nature of Jupiter’s core, or those of Neptune or Saturn for that matter. Perhaps TOI 849 b can teach us a thing or two about what gas giants look like beneath their thick atmosphere. At the very least, the new study shows that rocky cores exist, and astronomers can now be on the lookout for more.

The findings appeared in the journal Nature.

Updated: post corrected for spelling and language.

Jupiter’s Red Spot might not be a goner after all

The shrinking of the clouds that make up Great Red Spot on Jupiter has been well documented with photographic evidence from the last decade — but there’s no reason to believe it has drastically change its size or intensity, researchers say.

Jupiter, close-up of the Great Red Spot. Image credits: NASA / JPL.

Jupiter’s famous Red Spot is one of the most noticeable features inside our solar system. It’s a high-pressure region within Jupiter’s atmosphere, essentially a massive hurricane swirling wildly over Jupiter’s skies for 150 years — and perhaps much longer than that.

However, in recent times, astronomers have been signalling a concerning trend — well, concerning for Red Spot fans at least: the Red Spot appears to be disappearing. A recent study even pointed out that it dissipate within 20 years.

However, the news of the storm’s demise have been greatly exaggerated, one researcher believes.

Philip Marcus, from the University of California, Berkeley, believes that photos of the Red Spot (the main evidence for the shrinking) are not telling the whole story. Both professionals and amateur images, while very useful, don’t really describe the situation accurately.

A (false color) series of images capturing the repeated flaking of red clouds from the GRS in the Spring of 2019. In the earliest image, a flake on the east side of the giant red vortex is visible. The flake then breaks off from the GRS, but a new flake starts to detach in the fifth image. Credit: Chris Go

Many photos were showing large red “flakes” being ripped away from the storm, but according to Marcus, flaking is a natural phenomenon and not an indication of impending doom for a storm.

“I don’t think its fortunes were ever bad,” Marcus said. “It’s more like Mark Twain’s comment: The reports about its death have been greatly exaggerated.”

Marcus recently hosted a session called Shedding of Jupiter’s Red Flakes Does Not Mean It Is Dying at the American Physical Society’s Division of Fluid Dynamics 72nd Annual Meeting. He explained that smaller clouds sometimes bump into the Great Red Spot (GRS), creating stagnation points, where air movement suddenly stops, before restarting in different directions. These directions are consistent with the observed flakes.

“The loss of undigested clouds from the GRS through encounters with stagnation points does not signify the demise of the GRS,” he said. “The proximity of the stagnation points to the GRS during May and June does not signify its demise. The creation of little vortices to the east, northeast of the GRS during the spring of 2019 and their subsequent merging with the GRS with some does not signify its demise.”

However, there is a separate air circulation, driven by the heating and cooling above and below the vortex. This air circulation feeds the Great Red spot, allowing it to exist over the centuries and compensating for the decay of its energy.

It’s official: There’s water on Jupiter’s moon Europa

NASA has confirmed that Jupiter’s moon Europa contains liquid water, making it one of the most promising places we know for extraterrestrial life.

At first glance, not much is happening on Europa. A small, frozen world orbiting Jupiter doesn’t seem like the most interesting place out there. But 40 years ago, the Voyager snapped an intriguing photo of the satellite: its frozen surface wasn’t stale and monotonous, it was cracked and sliced by different features, suggesting active and recent phenomena. Subsequent missions showed even more exciting things.

Despite being undoubtedly bombarded by meteorites, Europa’s surface is largely devoid of craters. This means that something must have erased or eroded them, suggesting some active geology. Not only is Europa active — it has some form of tectonics, and more impressively, it seems to have liquid water. The liquid water isn’t on the surface but rather beneath the frozen surface. The pattern of the cracks observed on Europa’s surface suggest that the frozen surface of the planet is not locked to the rest of the interior, which is exactly what you’d expect to happen if a layer of liquid were to exist beneath the surface.

To make things even more tantalizing, astronomers have observed something which seems to be plumes of water emerging from Europa. Some of the plumes are hundreds of kilometers high, adding even more evidence to the case for water on Europa.

Now, that case is essentially proven. Researchers looking from the W. M. Keck Observatory, atop the dormant Mauna Kea volcano in Hawaii, found a clear signature of water molecules.

“Essential chemical elements (carbon, hydrogen, oxygen, nitrogen, phosphorus, and sulfur) and sources of energy, two of three requirements for life, are found all over the solar system. But the third — liquid water — is somewhat hard to find beyond Earth,” said Lucas Paganini, a NASA planetary scientist who led the water detection investigation. “While scientists have not yet detected liquid water directly, we’ve found the next best thing: water in vapor form.”

Image credits: NASA / JPL.

Detecting the signatures of elements on other planets is much more difficult than on Earth. Naturally, Europa’s environment is very different from that of Earth. The main idea behind the study was to use a spectrograph to assess the chemical composition of Europa by measuring how molecules on the satellite interact with infrared light. Molecules such as water emit specific frequencies which can be used as signatures.

But when your telescope is based on Earth, all light would pass through the Earth’s atmosphere — which contains a lot of water on its own. Paganini’s team had to use complex modeling to simulate the conditions of Earth’s atmosphere and then subtract them from what they were seeing on Europa. It wasn’t an easy task, but in the end, the researchers were successful.

Even so, they say, they’d like to get much closer to Europa to see what’s going on.

“We performed diligent safety checks to remove possible contaminants in ground-based observations,” said Avi Mandell, a Goddard planetary scientist on Paganini’s team. “But, eventually, we’ll have to get closer to Europa to see what’s really going on.”

They’ll get their wish fairly soon. NASA’s Clipper mission is set to launch in 2025, with the objective of analyzing Europa’s habitability and chemistry, as well as its geology. The mission will also aid in the selection of a landing site for the future Europa Lander, which, as the name implies, is scheduled to land on Europa to analyze it in unprecedented detail. Even before that, the ESA’s JUpiter ICy moons Explorer (JUICE) is set to launch in 2022, with the purpose of analyzing Jupiter’s Galilean moons: Ganymede, Callisto, and Europa.

For a period, the two spacecraft will both be orbiting Europa, enabling us to understand the satellite better than ever before. Hopefully, these missions could help answer one of the most tormenting questions in modern astronomy.

Europa, this small frozen rock orbiting Jupiter, has water. Could it have life?

Image credits: NASA / JPL.
Artist's composition of a volcanic exo-Io undergoing extreme mass loss. The hidden exomoon is enshrouded in an irradiated gas cloud shining in bright orange-yellow, as would be seen with a sodium filter. Patches of sodium clouds are seen to trail the lunar orbit, possibly driven by the gas giant's magnetosphere. (© University of Bern, Illustration: Thibaut Roger)

Astronomers find clues of a volcanically active exomoon

Artist’s composition of a volcanic exo-Io undergoing extreme mass loss. The hidden exomoon is enshrouded in an irradiated gas cloud shining in bright orange-yellow, as would be seen with a sodium filter. Patches of sodium clouds are seen to trail the lunar orbit, possibly driven by the gas giant’s magnetosphere. (© University of Bern, Illustration: Thibaut Roger)

A rocky extrasolar moon brimming with lava could orbit a planet 550 light-years from Earth, astronomers led by researchers from Bern University have discovered. 

The volcanically active exomoon could be hidden in the exoplanet system WASP-49b, orbiting a hot giant planet in the inconspicuous constellation of Lepus, underneath the bright Orion constellation.

The researchers describe the exomoon as an ‘extreme’ version of Jupiter’s moon Io — the most volcanically active body in our own solar system. Thus, painting a picture of an exotic and dangerous world — an ‘exo-Io’. 

Apurva Oza, a postdoctoral fellow at the Physics Insitute of the University of Bern and associate of the NCCR PlanetS, describes the exomoon, comparing it to a famous sci-fi setting: “It would be a dangerous volcanic world with a molten surface of lava — a lunar version of close-in Super-Earths like 55 Cancri-e. 

“A place where Jedis go to die, perilously familiar to Anakin Skywalker.”

More than a grain of sodium. Uniting theory and circumstantial evidence.

Astronomers have yet to discover a moon beyond our solar system meaning that the researchers base their suspicions of the existence of this exo-Io on circumstantial evidence — namely sodium gas in WASP-49b at an unusually high-altitude. 

Oza explains: “The neutral sodium gas is so far away from the planet that it is unlikely to be emitted solely by a planetary wind.

“The sodium is right where it should be.”

Comparing this feature to observations of the Jupiter and Io system using low-mass calculations demonstrated to the team that an exo-Io could, indeed, be a plausible mechanism for sodium at WASP-49b. 

The theory that large amounts of sodium around an exoplanet could point to a hidden moon or a ring of material was advance by Bob Johnson and Patrick Huggins in 2006. Following this, researchers from the University of Virginia calculated that a three-body system comprised of a star, close giant planet and a moon could remain stable for billions of years. 

Oza took these theoretical predictions to form the basis of he and his colleagues’ work — published in the Astrophysical Journal. 

The astrophysicist explains: “The enormous tidal forces in such a system are the key to everything.

“The energy released by the tides to the planet and its moon keeps the moon’s orbit stable, simultaneously heating it up and making it volcanically active.”

The researchers also demonstrate in their study that a small rocky moon would eject more sodium and potassium into space via this extreme volcanism than a large gas planet. This would especially be the case at high altitudes. 

These emissions can then be identified by astronomers using the technique of spectroscopy. These particular elements are particularly useful to astronomers. 

Oza adds: “Sodium and potassium lines are quantum treasures to us astronomers because they are extremely bright.

“The vintage street lamps that light up our streets with yellow haze, is akin to the gas we are now detecting in the spectra of a dozen exoplanets.”

When comparing their calculations with actual observations of sodium and potassium, the team found five candidate systems where a hidden exomoon could survive thermal evaporation. In the case of WASP-49b, the best explanation for the observed data was the presence of an exo-Io. 

This isn’t the only explanation, however. As mention above, the observations of sodium at high altitudes could instead indicate the exoplanet is surrounded by a ring of material — most likely ionised gas. 

Oza admits that the team need to find more clues, and as such, are relying on future observations with both ground and space-based telescopes. Also, as a few of these exo-Ios could eventually be destroyed as a result of extreme mass-loss, the team also want to search for evidence of such destruction. 

Oza concludes: “While the current wave of research is going towards habitability and biosignatures, our signature is a signature of destruction.

“The exciting part is that we can monitor these destructive processes in real-time, like fireworks.”

Original research: https://arxiv.org/pdf/1908.10732.pdf

Jupiter once absorbed a whole planet, new data suggests

There’s more to the gas giant than meets the eye — Jupiter might have had a violent youth which included a cataclysmic collision with another planet.

Image credits: NASA/JPL.

Researchers have been studying Jupiter for more than a century, but NASA’s Juno spacecraft enabled astronomers to understand the gas giant in unprecedented detail. Among the peculiarities of Jupiter is its fuzzy core.

Unlike the neat, almost-spherical core that astronomers would have expected, the planet features a fuzzy center — a bizarre mix of solid rocks and hydrogen gas.

“We have been studying the giant planets, particularly Jupiter and Saturn, since the time of Galileo, but we still don’t know exactly how they formed,” said Rice University astronomer and study co-author Andrea Isella.

Many astronomers believe Jupiter began as a dense, rocky planet. It slowly gathered a thick atmosphere from the gas and dust in the primordial solar system, growing larger and larger and forming what we see today. Meanwhile, others believe that Jupiter formed from a collapse of a fraction of the disk. In this case, Jupiter’s core wouldn’t have been rocky from the start, it would just have become increasingly dense as gravity dragged heavier elements towards the center of the planet.

However, neither of these theories do a very good job of explaining why the core looks the way it does today.

Jupiter core computer models
Models of Jupiter’s core suggest a cataclysmic collision is plausible. Credits: Shang-Fei Liu/Sun Yat-Sen University.

Instead, another possible explanation is a cataclysmic collision some 4.5 billion years ago with a planet 10 times the mass of the Earth. Back then, Jupiter would have been very young and probably surrounded by several protoplanets that are long gone. Isella and colleagues carried out computer models showing that in the event of such a collision, their cores would have combined and diffused after only 10 hours.

This would also help explain another dilemma regarding Jupiter: how its surface became so rich in elements such as nitrogen and carbon. After the collision, cooling and winds would have updrafted some of the fuzzy core upward, bringing the elements towards the surface.

“Models of such a scenario lead to an internal structure that is consistent with a diluted core, persisting over billions of years,” the team writes in the study.

Of course, while the collision idea fits the data very well and is very plausible, there are other mechanisms which could explain Jupiter’s structure. However, it’s worth noting that many astronomers suspect that the early solar system was violent, with numerous planetary collisions. This is strongly suggested by the tilt of planets such as Uranus, but it seems that even without a tilt, Jupiter wasn’t spared from the protoplanetary carnage.

“We suggest that collisions were common in the young Solar System and that a similar event may have also occurred for Saturn, contributing to the structural differences between Jupiter and Saturn,” the team concludes.

The study was published in Nature.

Birthplace of giant planets: Monash astrophysicists discover a baby planet sculpting a disc of gas and dust. Credit: ESO/ALMA.

‘Baby’ planet two to three times the size of Jupiter discovered

It may be an infant, but that doesn’t mean it’s small. Researchers have discovered a new ‘baby’ planet, at least twice the size of Jupiter, carving a path through a stellar nursery. 

Astrophysicists from Monash University have used the ALMA telescope in Chile to discover a ‘baby’ planet inside a protoplanetary disc. But despite being a youngster, this infant is still between two to three times the mass of Jupiter — the most massive planet in our solar system. 

Birthplace of giant planets: Monash astrophysicists discover a baby planet sculpting a disc of gas and dust. Credit: ESO/ALMA.

The giant ‘baby’ was found inside in the middle of a gap in the gas and dust that forms the planet-forming disc around the young star HD97048. The study — published in Nature Astronomy — is the first to provide an origin of these gaps in protoplanetary discs — also known as ‘stellar nurseries’ because they act as the birthplaces for planets— which have thus far puzzled astronomers. 

“The origin of these gaps has been the subject of much debate,” says the study’s lead author, Dr Christophe Pinte, an ARC Future Fellow at the Monash School of Physics and Astronomy. “Now we have the first direct evidence that a baby planet is responsible for carving one of these gaps in the disc of dust and gas swirling around the young star.”

The team discovered the new planet by mapping the flow of gas around HD97048 — a young star not yet on the main sequence, which sits in the constellation Chamaeleon located over 600 light-years from Earth. 

Observing the flow in this material, the team hunted for areas in which the flow was disturbed, in a similar way to disturbance a submerged rock would cause in a stream flowing over it. They were able to ascertain the planet’s size by recreating this ‘bump’ or ‘kink’ in the flow using computer models. 

Using the same method of locating ‘bumps’ in gas flow around young stars, the team previously discovered a similar new ‘baby’ planet around another young star roughly a year ago. Those findings were published in the Astrophysical Journal Letters.

That initial discovery — found in the stellar nursery around HD163296 360 light-years from Earth — was the first of its kind and provided a ‘missing link’ in scientists understanding of planet formation.

These two studies add to what is only a small collection of known ‘baby’ planets. 

“There is a lot of debate about whether baby planets are really responsible for causing these gaps,” says Associate Professor Daniel Price, the study’s co-author and Future Fellow at the school. “Our study establishes for the first time a firm link between baby planets and the gaps seen in discs around young stars.”

Original research: https://www.nature.com/articles/s41550-019-0852-6


Hubble snaps breathtaking new image of Jupiter

Jupiter is still pretty, science finds.


Image credits NASA, ESA / A. Simon (Goddard Space Flight Center) and M.H. Wong (University of California, Berkeley)

The image was taken on June 27, 2019 and centers on the planet’s titanic Great Red Spot. It records Jupiter’s color palette, swirling clouds, and turbulent atmosphere in much higher quality than previously-available images. These elements provide an important glimpse into the processes unfurling in the gas giant’s atmosphere.

Ten year challenge photo

The image was taken in visible light as part of the Outer Planets Atmospheres Legacy program (OPAL). It was snapped with Hubble’s Wide Field Camera 3 when Jupiter was 400 million miles from Earth — near “opposition,” or almost directly opposite the Sun in the sky.

OPAL generates global views of the outer planets each year using the Hubble Telescope, which are meant to provide researchers with the data they need to track changes in their storm, wind, and cloud dynamics.

One of Jupiter’s most striking features is the Great Red Spot, around which the current image focuses. The Spot is a churning storm, rolling counterclockwise between two bands of clouds (above and below the Great Red Spot) which are moving in opposite directions. The red band to the northeast of the Great Red Spot contains clouds moving westward and around the north of the giant tempest. The white clouds to its southwest are moving eastward to the south of the spot. The swirling filaments seen around its outer edge are high-altitude clouds that are being pulled in and around the storm.

Jupiter’s bands are created by differences in the thickness and height of the ammonia ice clouds that blanket its surface, both properties dictated by local variations in atmospheric pressure. The more colorful bands and are generally ‘deeper’ clouds. Lighter bands rise higher and are thicker, generally, than the darker ones. 

Winds between bands can reach speeds of up to 400 miles (644 kilometers) per hour. All of the bands seen in this image are corralled to the north and to the south by powerful, constant jet streams — these remain stable even as the bands change color on the other side of the planet.  The band of deep red and bright white that border the Giant Red Spot also become much fainter on the other side of Jupiter.

You can learn more about how these colors form here.