In July 2016, NASA’s Juno space probe reached Jupiter, becoming the second spacecraft in history to orbit the gas giant (the first being the Galileo probe that orbited Jupiter from 1995 to 2003). The data it has sent back has led to new revelations about the Jovian atmosphere, magnetosphere, gravitational field, structure, and composition. While its primary mission was intended to only last until 2018, a mission extension means that Juno will continue to orbit Jupiter’s poles (a perijove maneuver) and send back stunning images and data until 2025.
Recently, a team of citizen scientists led by mathematician and software developer Gerald Eichstädt used images taken by the probe’s visible-light camera/telescope (the JunoCam) to create a 3D animation of Jupiter’s upper atmosphere. Eichstädt’s animation was presented at the 2022 Europlanet Science Congress (EPSC), which took place from September 18 – 23 in Granada, and shows the relative heights of the cloud tops of Jupiter that reveal delicately textured swirls and peaks. Eichstädt’s work also showcased the potential for citizen science and public engagement with today’s missions.
Jupiter is composed almost entirely of hydrogen and helium. The amounts of each closely conform to the theoretical quantities in the primordial solar nebula. But it also contains other heavier elements, which astronomers call metals. Even though metals are a small component of Jupiter, their presence and distribution tell astronomers a lot.
According to a new study, Jupiter’s metal content and distribution mean that the planet ate a lot of rocky planetesimals in its youth.
Many papers are usually released at once for big space exploration missions. Usually, that happens when an entire batch of data has been analyzed. The most recent set of papers is from Juno’s explorations of Jupiter’s atmosphere. With this data dump, scientists now have the first 3D map of the atmosphere of the solar system’s largest planet.
For decades, scientists engaged in the search for life in the Universe (aka. astrobiology) have focused on searching for life on other Earth-like planets. These included terrestrial (aka. rocky) planets beyond our Solar System (extrasolar planets) and ones here at home. Beyond Earth, Mars is considered to be the most habitable planet next to Earth, and scientists have also theorized that life could exist (in microbial form) in the cloud tops of Venus.
In all cases, a major focal point is whether or not planets have large bodies of water on their surfaces (or did in the past). However, a new study led by a research team from the UK and German (with support from NASA) has shown that the existence of life may have less to do with the quantity of water and more to with the presence of atmospheric water molecules. As a result, we may have better luck finding life on Jupiter’s turbulent cloud deck than Venus’.
Timing is extraordinarily important in many aspects of astronomy. If an astronomer or their instrument is looking the wrong way at the wrong time they could miss something spectacular. Alternatively, there are moments when our instruments capture something unexpected in regions of space that we were searching for something else. That is exactly what happened recently when a team of scientists, led by Rohini Giles at the Southwest Research Institute, saw an image of what is likely a meteor impacting Jupiter’s atmosphere.
The venerable Hubble Space Telescope has given us another gorgeous picture of Jupiter and its moon Europa. The incredibly sharp image was captured on August 25th, and shows some of the stunning detail in Jupiter’s stormy atmosphere. Hidden in all that stormy activity is something new: a bright white storm plume travelling at about 560 km/h (350 mp/h).
Most massive planet in the solar system – twice that of all the other planets combined. This giant world formed from the same cloud of dust and gas that became our Sun and the rest of the planets. But Jupiter was the first-born of our planetary family. As the first planet, Jupiter’s massive gravitational field likely shaped the rest of the entire solar system. Jupiter could’ve played a role in where all the planets aligned in their orbits around the Sun…or didn’t as the asteroid belt is a vast region which could’ve been occupied by another planet were it not for Jupiter’s gravity. Gas giants like Jupiter can also hurl entire planets out of their solar systems, or themselves spiral into their stars. Saturn’s formation several million years later probably spared Jupiter this fate. Jupiter may also act as a “comet catcher.” Comets and asteroids which could otherwise fall toward the inner solar system and strike the rocky worlds like Earth are captured by Jupiter’s gravitational field instead and ultimately plunge into Jupiter’s clouds. But at other times in Earth’s history, Jupiter may have had the opposite effect, hurling asteroids in our direction – typically a bad thing but may have also resulted in water-rich rocks coming to Earth that led to the blue planet we know of today.
It’s difficult to imagine the magnitude of storms on Jupiter. The gas giant’s most visible atmospheric feature, the Great Red Spot, may be getting smaller, but one hundred years ago, it was about 40,000 km (25,000 miles) in diameter, or three times Earth’s diameter.
Jupiter’s atmosphere also features thunderheads that are five times taller than Earth’s: a whopping 64 km (40 miles) from bottom to top. Its atmosphere is not entirely understood, though NASA’s Juno spacecraft is advancing our understanding. The planet may contain strange things like a layer of liquid metallic hydrogen.
Now a group of scientists are combining the power of the Hubble Space Telescope, the Gemini Observatory and the Juno spacecraft to probe Jupiter’s atmosphere, and the awe-inspiring storms that spawn there.
For centuries, astronomers have been observing Jupiter swirling surface and been awed and mystified by its appearance. The mystery only deepened when, in 1995, the Galileo spacecraft reached Jupiter and began studying its atmosphere in depth. Since that time, astronomers have puzzled over its colored bands and wondered if they are just surface phenomenon, or something that goes deeper.
Thanks to the Juno spacecraft, which has been orbiting Jupiter since July of 2016, scientists are now much closer to answering that question. This past week, three new studies were published based on Juno data that presented new findings on Jupiter’s magnetic field, its interior rotation, and how deep its belts extend. All of these findings are revising what scientists think of Jupiter’s atmosphere and its inner layers.
The research effort was led by Professo Kaspi and Dr. Galanti, who in addition to being the lead authors on the second study were co-authors on the other two. The pair have been preparing for this analysis even before Juno launched in 2011, during which time they built mathematical tools to analyze the gravitational field data and get a better grasp of Jupiter’s atmosphere and its dynamics.
All three studies were based on data gathered by Juno as it passed from one of Jupiter’s pole to the other every 53-days – a maneuver known as a “perijove”. With each pass, the probe used its advanced suite of instruments to peer beneath the surface layers of the atmosphere. In addition, radio waves emitted by the probe were measured to determine how they were shifted by the planet’s gravitational field with each orbit.
As astronomers have understood for some time, Jupiter’s jets flow in bands from east to west and west to east. In the process, they disrupt the even distribution of mass on the planet. By measuring changes in the planet’s gravity field (and thus this mass imbalance), Dr. Kaspi and Dr. Galanti’s analytical tools were able to calculate how deep the storms extend beneath the surface and what it’s interior dynamics are like.
Above all, the team expected to find anomalies because of the way the planet deviates from being a perfect sphere – which is due to how its rapid rotation squishes it slightly. However, they also looked for additional anomalies that could be explained due to the presence of powerful winds in the atmosphere.
In the first study, Dr. Iess and his colleagues used precise Doppler tracking of the Juno spacecraft to conduct measurements of Jupiter’s gravity harmonics – both even and odd. What they determined was Jupiter’s magnetic field has a north-south asymmetry, which is indicative of interior flows in the atmosphere.
Analysis of this asymmetry was followed-up on in the second study, where Dr. Kaspi, Dr. Galanti and their colleagues used the variations in the planet’s gravity field to calculate the depth of Jupiter’s east-west jet streams. By measuring how these jets cause an imbalance in Jupiter’s gravity field, and even disrupt the mass of the planet, they concluded that they extend to a depth of 3000 km (1864 mi).
From all this, Prof. Guillot and his colleagues conducted the third study, where they used the previous findings about the planet’s gravitational field and jet streams and compared the results to predictions of interior models. From this, they determined that the interior of the planet rotates almost like a rigid body and that differential rotation decreases farther down.
In addition, they found that the zones of atmospheric flow extended to between 2,000 km (1243 mi) and 3,500 km (2175 mi) deep, which was consistent with the constraints obtained from the odd gravitational harmonics. This depth also corresponds to the point where electric conductivity would become large enough that magnetic drag would suppress differential rotation.
Based on their findings, the team also calculated that Jupiter’s atmosphere constitutes 1% of its total mass. For comparison, Earth’s atmosphere is less than a millionth of its total mass. Still, as Dr. Kaspi explained in Weizzmann Institute press release, this was rather surprising:
“That is much more than anyone thought and more than what has been known from other planets in the Solar System. That is basically a mass equal to three Earths moving at speeds of tens of meters per second.”
All told, these studies have shed new light on the Jupiter’s atmospheric dynamics and interior structure. At present, the subject of what resides at Jupiter’s core remains unresolved. But the researchers hope to analyze further measurements made by Juno to see whether Jupiter has a solid core and (if so) to determine its mass. This in turn will help astronomers learn a great deal about the Solar System’s history and formation.
In addition, Kaspi and Galanti are looking to use some of the same methods they developed to characterize Jupiter’s jet streams to tackle its most iconic feature – Jupiter’s Great Red Spot. In addition to determining how deep this storm extends, they also hope to learn why this storm has persisted for so many centuries, and why it has been noticeably shrinking in recent years.
The Juno mission is expected to wrap up in July of 2018. Barring any extensions, the probe will conduct a controlled deorbit into Jupiter’s atmosphere after conducting perijove 14. However, even after the mission is over, scientists will be analyzing the data it has collected for years to come. What this reveals about the Solar System’s largest planet will also go a long way towards informing out understanding of the Solar System.
Since it established orbit around Jupiter in July of 2016, the Juno mission has been sending back vital information about the gas giant’s atmosphere, magnetic field and weather patterns. With every passing orbit – known as perijoves, which take place every 53 days – the probe has revealed more interesting things about Jupiter, which scientists will rely on to learn more about its formation and evolution.
Ever since astronomers began observing Jupiter with powerful telescopes, they have been aware of its swirling, banded appearance. These colorful stripes of orange, brown and white are the result of Jupiter’s atmospheric composition, which is largely made up of hydrogen and helium but also contains ammonia crystals and compounds that change color when exposed to sunlight (aka. chromofores).
Until now, researchers have been unclear as to whether or not these bands are confined to a shallow layer of the atmosphere or reach deep into the interior of the planet. Answering this question is one of the main goals of the Juno mission, which has been studying Jupiter’s magnetic field to see how it’s interior atmosphere works. Based on the latest results, the Juno team has concluded that hydrogen-rich gas is flowing asymmetrically deep in the planet.
Another interesting find was that Jupiter’s gravity field varies with depth, which indicated that material is flowing as far down as 3,000 km (1,864 mi). Combined with information obtained during previous perijoves, this latest data suggests that Jupiter’s core is small and poorly defined. This flies in the face of previous models of Jupiter, which held that the outer layers are gaseous while the interior ones are made up of metallic hydrogen and a rocky core.
As Tristan Guillot – a planetary scientist at the Observatory of the Côte d’Azur in Nice, France, and a co-author on the study – indicated during the meeting, “This is something that was not expected. We were not sure at all whether we would be able to see that… It’s clear that giant planets have a lot of secrets.”
But of course, more passes and data are needed in order to pinpoint how strong the flow of gases are at various depths, which could resolve the question of how Jupiter’s interior is structured. In the meantime, the Juno scientists are pouring over the probe’s gravity data hoping to see what else it can teach them. For instance, they also want to know how far the Great Red Spot extends into the amotpshere.
This anticyclonic storm, which was first spotted in the 17th century, is Jupiter’s most famous feature. In addition to being large enough to swallow Earth whole – measuring some 16,000 kilometers (10,000 miles) in diameter – wind speeds can reach up to 120 meters per second (432 km/h; 286 mph) at its edges. Already the JunoCam has snapped some very impressive pictures of this storm, and other data has indicated that the storm could run deep.
In fact, on July 10th, 2017, the Juno probe passed withing 9,000 km (5,600 mi) of the Great Red Spot, which took place during its sixth orbit (perijove six) of Jupiter. With it’s suite of eight scientific instruments directed at the storm, the probe obtained readings that indicated that the Great Red Spot could also extend hundreds of kilometers into the interior, or possibly even deeper.
As David Stevenson, a planetary scientist at the California Institute of Technology and a co-author on the study, said during the meeting, “It’s not yet clear that it is so deep it will show up in gravity data. But we’re trying”.
Other big surprises which Juno has revealed since it entered orbit around Jupiter include the clusters of cyclones located at each pole. These were visible to the probe’s instruments in both the visible and infrared wavelengths as it made its first maneuver around the planet, passing from pole to pole. Since Juno is the first space probe in history to orbit the planet this way, these storms were previously unknown to scientists.
In total, Juno spotted eight cyclonic storms around the north pole and five around the south pole. Scientists were especially surprised to see these, since computer modelling suggests that such small storms would not be stable around the poles due to the planet’s swirling polar winds. The answer to this, as indicated during the presentation, may have to do with a concept known as vortex crystals.
As Fachreddin Tabataba-Vakili – a planetary scientist at NASA’s Jet Propulsion Laboratory and a co-author on the study – explained, such crystals are created when small vortices form and persist as the material in which they are embedded continues to flow. This phenomenon has been seen on Earth in the form of rotating superfluids, and Jupiter’s swirling poles may possess similar dynamics.
In the short time that Juno has been operating around Jupiter, it has revealed much about the planet’s atmosphere, interior, magnetic field and internal dynamics. Long after the mission is complete – which will take place in February of 2018 when the probe is crashed into Jupiter’s atmosphere – scientists are likely to be sifting through all the data it obtained, hoping to solve any remaining mysteries from the Solar System’s largest and most massive planet.