New Discoveries Puts Jupiter at 92 Known Moons

A top-down overhead view of the orbits of Jupiter's 92 moons. Credit: Scott Sheppard.

The moon hunter strikes again.

A team of astronomers led by Scott Sheppard of the Carnegie Institution has found and confirmed 12 new moons orbiting Jupiter, bringing the total of moons at the giant planet to 92. The new moons were quietly announced on the International Astronomical Union’s Minor Planet Center website last week, and the new discoveries puts Jupiter in the lead in a recent back-and-forth moon battle with Saturn.

Jupiter was solidly in the lead with Sheppard and team’s announcement of 12 new moons back in 2018, but then in 2019, Sheppard and colleagues found a whopping 20 new moons orbiting Saturn, bringing the ringed planet’s total number of moons to 82. But now this latest addition moves Jupiter back in the lead.

With Sheppard around, we may never know the final count.

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An Ongoing Study of Jupiter’s Cloudtops Has Been Going on for 40 Years

A Hubble Space Telescope image of Jupiter in 2020. Planetary scientists studied temperature changes in its lower atmosphere and may soon be able to predict Jupiter weather. Credit: NASA, ESA, A. Simon (Goddard Space Flight Center), and M. H. Wong (University of California, Berkeley) and the OPAL team.
A Hubble Space Telescope image of Jupiter in 2020. Planetary scientists studied temperature changes in its lower atmosphere and may soon be able to predict Jupiter weather. Credit: NASA, ESA, A. Simon (Goddard Space Flight Center), and M. H. Wong (University of California, Berkeley) and the OPAL team.

Some of the most useful discoveries about distant objects take time to complete. For example, several generations of planetary scientists have been studying the clouds of Jupiter since the late 1970s. Their observations focused on the planet’s upper troposphere. The results show unexpected patterns in how the temperatures of Jupiter’s belts and zones change over time.

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Juno’s has Been Touring Jupiter’s Moons on its Extended Mission. Next Stop: Volcanic Io

The Juno mission's infrared view of the Jovian moon Io. Taken on July 5, 2022. All the hotspots are volcanic features. Courtesy NASA/JPL-Caltech/SwRI/ASI/INAF/JIRAM
The Juno mission's infrared view of the Jovian moon Io. Taken on July 5, 2022. All the hotspots are volcanic features. Courtesy NASA/JPL-Caltech/SwRI/ASI/INAF/JIRAM

For a tiny moon orbiting a giant planet, Io sure packs a giant wallop. It’s the most volcanic world in the solar system. Due to that extreme volcanism, scientists with the Juno mission are now focusing the spacecraft’s instruments and cameras on Io. They want to know more about its eruptions and how its constant stream of material into space interacts with Jupiter’s magnetosphere.

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New Views of Ganymede and Europa From Earth’s Most Powerful Telescope

Scouting mission locations in the outer solar system is complicated. It is difficult to know what you find before you get there with a probe, and once you’re already there, changing trajectories to look at the most exciting parts of the system is difficult. A much better option would be to map out the system in detail before the probe arrives. That is precisely what a team at the University of Leicester is doing in the expectation of the arrival of the JUICE and Europa Clipper probes to the Jupiter system.

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Mars Express Watched Deimos Pass in Front of Jupiter and its Moons

Deimos
Deimos, as seen by Mars Express. Credit: ESA.

That’s no moon … wait … yes, it is, and more!

ESA’s Mars Express has captured an unusual and rare occultation, all from its vantage point in orbit of Mars.  The spacecraft’s orbit brought it to the right place where it could witness the moment Mars’ small moon Deimos passed in front of Jupiter and its four largest moons. Scientists say that celestial alignments like these enable a more precise determination of the Martian moons’ orbits.

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Jupiter’s Atmosphere is Surprisingly Hot

Temperature measurements of Jupiter's upper atmosphere. Credit: James O’Donoghue

Jupiter is a big planet, but it’s still a planet. That means it doesn’t heat itself through fancy mechanisms like nuclear fusion. Its interior is heated through its own weight, squeezing the interior through hydrostatic equilibrium, and its surface is heated mostly by the Sun. Since Jupiter only gets about 4% of the light per square meter that Earth gets, you’d expect its upper atmosphere to be pretty cold. Traditional models estimate it should be about -70 degrees Celsius. But recent measurements show the upper atmosphere is over 400 degrees Celsius, and in the polar regions as much as 700 degrees Celsius. In the words of Ruby Rhod from the movie The Fifth Element, “It’s Hot Hot Hot!”

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A Fascinating Look at Jupiter's Clouds Where the Light Intensity is Converted Into 3D

A still image from the 3D animation that shows the elevation of Jupiter's cloud tops. Credit: NASA/JPL-Caltech/SwRI/MSSS/Gerald Eichstädt

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.

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Webb Telescope Sees Jupiter and Its Auroras in a New Light

JWST view of Jupiter
The James Webb Space Telescope's NIRCam imager produced this composite image of the Jupiter system using orange and cyan filters. The image shows Jupiter's auroras as bright rims at the poles. The planet's rings and two of its moons, Amalthea and Adrastea, are also visible. Credit: NASA, ESA, CSA, Jupiter ERS Team; image processing by Ricardo Hueso (UPV/EHU) and Judy Schmidt.

NASA’s James Webb Space Telescope is designed to probe the farthest frontiers of the universe, but newly released images of Jupiter prove that the observatory can also bring fresh perspectives to more familiar celestial sights.

The infrared images reveal Jupiter’s polar auroras and its faint rings as well as two of its moons — plus some galaxies in the far background. The planet’s Great Red Spot is there as well, but because it’s seen through three of JWST’s specialized filters, it looks white rather than red.

JWST’s new perspective should give scientists a better sense of how the complex Jupiter system is put together.

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Jupiter Missions Could Also Help Search for Dark Matter

In a recent study published in the Journal of High Energy Physics, two researchers from Brown University demonstrated how data from past missions to Jupiter can help scientists examine dark matter, one of the most mysterious phenomena in the universe. The reason past Jupiter missions were chosen is due to the extensive amount of data gathered about the largest planet in the solar system, most notably from the Galileo and Juno orbiters. The elusive nature and composition of dark matter continues to elude scientists, both figuratively and literally, because it does not emit any light. So why do scientists continue to study this mysterious—and completely invisible—phenomena?

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Jupiter's Giant Moons Prevent it From Having Rings Like Saturn

Saturn and its system of rings, acquired by the Cassini probe. Credit: NASA/JPL-Caltech

When the name Saturn is uttered, what comes to mind? For most people, the answer would probably be, “its fabulous system of rings.” There’s no doubt they are iconic, but what is perhaps lesser-known is that Jupiter, Uranus, and Neptune all have ring systems of their own. However, whereas Saturn’s rings are composed mainly of ice particles (making them highly reflective), Jupiter’s rings are composed mainly of dust grains. Meanwhile, Uranus and Neptune have rings of extremely dark particles known as tholins that are very hard to see. For this reason, none of the other gas giants get much recognition for their rings.

However, the question of why Jupiter doesn’t have larger, more spectacular rings than Saturn has been bothering astronomers for quite some time. As the larger and more massive of the two bodies, Jupiter should have rings that would dwarf Saturn’s by comparison. This mystery may have finally been resolved thanks to new research by a team from UC Riverside. According to their study, Jupiter’s massive moons (aka. Jupiter’s Galilean Moons) prevented it from developing a big, bright, beautiful ring system that would put Saturn’s to shame.

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