This composite was created with images from NASA’s Juno mission and shows the shadow of Jupiter cast by Io, one of its many moons.
NASA/JPL-Caltech/SwRI/MSSS/Kevin M. Gill
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NASA/JPL-Caltech/SwRI/MSSS/Kevin M. Gill
This composite was created with images from NASA’s Juno mission and shows the shadow of Jupiter cast by Io, one of its many moons.
NASA/JPL-Caltech/SwRI/MSSS/Kevin M. Gill
Scientists have spotted 12 more moons around Jupiter, adding to an already huge number of moons that appears to be growing.
There are so many moons around this giant gas planet that astronomer Scott Sheppard is having a hard time keeping track of them.
“With this new haul, I believe, we’re up to 92… actually, I’ll have to check,” he said as he bent to type on his computer at the Carnegie Institution for Science, Earth and Planets Laboratory in Washington DC. “Yeah, so 92 is the number we have right now.”
His team is currently tracking several more moons that, once confirmed in the next year or two, will put Jupiter in the top 100.
There’s a good reason to keep looking for more moons, Sheppard said: If moons are found in suitable orbits, spacecraft on missions to Jupiter could fly closer and peek, so scientists can find out what the tiny moons are made of.
This is important because Jupiter’s small outer moons are quite mysterious. Astronomers suspect that they are remnants of the original building materials used to form the largest planet in the solar system.
Sheppard has been discovering new moons around Jupiter for more than two decades, so much so that some of his colleagues jokingly call him “Galileo,” after the famous astronomer who first discovered that Jupiter had moons in 1610.
Every few years, Sheppard and his fellow astronomers take advantage of better technology and larger telescopes to add more moons to their tally. Currently, Jupiter holds the record for the most known moon, beating Saturn’s 83 moons.
Unlike the four large “Galilean” moons, which have some dramatic features such as volcanoes and subsurface oceans, the moon Sheppard discovered is small and orbits far away.
A “moon” is defined as an object orbiting a planet, he said, but beyond that, astronomers haven’t really discussed how big an object should be to count.
“One thing I would like to say is that the International Astronomical Union has decided that they will not name moons that are less than 1 kilometer across,” he said.
Some of the moons he found around Jupiter were that big — a person could pass through them in about twelve minutes. From Earth, these small moons look like points of light.
“These objects are jagged, elongated, with the possibility of many craters on the surface,” he said.
It is most likely a fragment or shard of a once larger object. The way these moons move around Jupiter in groups suggests that each group is the remnant of a once larger moon.
“We thought initially there were just a handful of parent moons that were bombarded by other moons or comets that were older than the solar system and then broke up,” he said.
However, where the original moons came from is still unclear. “These outer moons, we believe, did not form together with the planet. “We think the planet captured it,” Sheppard said.
The more moons he discovered, the more likely they were to be on or near the spacecraft’s path to Jupiter.
Several spacecraft will soon venture there to study the planet’s larger icy moons, which orbit closer to the planet. The European Space Agency’s JUICE mission is scheduled to launch in April, and next year NASA is sending a probe to Europa.
One of the strangest moons discovered around Jupiter, and Sheppard’s personal favorite, is a strange moon that moves without a companion.
“It orbits very far from the planet and is in a region where everyone is moving in the opposite direction. So it’s like going against the flow of traffic,” said Marina Brozovic, a physicist at NASA’s Jet Propulsion Laboratory, which calculated the planet’s orbit. outer moon.
He pointed out that the number of Saturn’s moons is also increasing. After a new group of Saturn’s moons was announced in 2019, it took the record for most famous moon from Jupiter. Now Jupiter has the title again.
“It’s like a little race between Jupiter and Saturn: who has more moons?” Brozovic said, noting that several researchers recently conducted theoretical studies that found that Saturn should eventually have more fragments, as recent collisions would likely have produced fragments.
Between Jupiter and Saturn, he says, there are probably hundreds more moons waiting to be discovered. And Uranus and Neptune must also have undetected outer moons. But it’s so far away, it’s hard to see it.
Sheppard said that he and his colleagues have looked for unknown small moons around other planets, such as Mars and Venus – without finding any – and they plan to look around Mercury in the coming months.
“We just finished working on Uranus and Neptune,” he said. “So keep watching. Some interesting things might come up in the future.”
2023-10-26 10:22:15
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