Jupiter's moon count jumps to 92, breaking Saturn's Solar System Record.

Extract from  ABC News

Posted  4 Feb 2023 at 11:01am

The Solar System's largest planet is now confirmed to have the most known moons.(AP: NASA, ESA, A Simon/Goddard Space Flight Center, MH Wong/University of California, Berkeley)

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Astronomers have discovered 12 new moons around Jupiter, putting the total count at a record-breaking 92.

Key points:

• The moons were discovered in 2021 and 2022 and confirmed with follow-up observations of their orbits
• One of the researchers who discovered the moons expects to add to the tally for both Jupiter and Saturn
• Many moons around the four gas giants are believed to have been formed by larger moons breaking up after colliding with one another, asteroids or comets

That is more than any other planet in our solar system. Saturn, the one-time leader, comes in a close second with 83 confirmed moons.

Jupiter's moons were added recently to a list kept by the International Astronomical Union's Minor Planet Center, said Scott Sheppard of the Carnegie Institution, who was part of the team.

They were discovered using telescopes in Hawaii and Chile in 2021 and 2022, and their orbits were confirmed with follow-up observations.

These newest moons range in size from 1 kilometre to 3 kilometres, according to Dr Sheppard.

"I hope we can image one of these outer moons close-up in the near future to better determine their origins," he said in an email on Friday.

In April, the European Space Agency is sending a spacecraft to Jupiter to study the planet and some of its biggest, icy moons.

And next year, NASA will launch the Europa Clipper to explore Jupiter's moon of the same name, which could harbour an ocean beneath its frozen crust.

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Dr Sheppard — who discovered a slew of moons around Saturn a few years ago and has taken part in 70 moon discoveries so far around Jupiter — expects to keep adding to the lunar tally of both gas giants.

Jupiter and Saturn are loaded with small moons, believed to be fragments of once bigger moons that collided with one another or with comets or asteroids, Dr Sheppard said.

The same goes for Uranus and Neptune, but they are so distant that it makes moon-spotting even harder.

For the record, Uranus has 27 confirmed moons, Neptune 14, Mars two and Earth one. Venus and Mercury come up empty.

Pluto, which was demoted from planet to dwarf planet in 2006, is itself only one-sixth the size of Earth's Moon but has five known satellites of its own. 

Jupiter's newly discovered moons have yet to be named.

Dr Sheppard said only half of them were big enough — at least 1 mile (1.5 kilometres) or so — to warrant a name.

Saturn, with its famous rings, has been demoted to second-most moons of any planet in the Solar System.(Reuters: NASA/JPL-Caltech/Space Science Institute)

AP/ABC