Saturn overtakes Jupiter as planet with most moons as scientists discover 20 more in its orbit

'Moon king': Saturn is now known to be the planet with the most moons in its orbit, overtaking Jupiter
NASA

Saturn has overtaken Jupiter as the planet with the most moons, US researchers have found.

A team of scientists this summer discovered 20 new moons orbiting the ringed planet, bring its total to 82.

This means it has leapt ahead of Jupiter, which has 79, to become the “true moon king”.

"It was fun to find that Saturn is the true moon king," said astronomer Scott Sheppard of the Carnegie Institution for Science.

Jupiter was previously thought to be the planet in our solar system with the most moons
NASA

Jupiter still has the biggest moon of any planets in our solar system.

Ganymede, which is not only the largest moon but the ninth largest object in the solar system, is nearly half the size of Earth.

By contrast, Saturn's 20 new moons are minuscule, each barely three miles in diameter.

Mr Sheppard and his team used a telescope in Hawaii to spot Saturn's 20 new moons over the summer.

About 100 even tinier moons may be orbiting Saturn, still waiting to be found, he said.

Astronomers have almost completed the inventory of moons as small as three miles around Saturn and one mile around Jupiter, according to Mr Sheppard.

Future larger telescopes will be needed to see anything smaller.

It is harder to spot “mini” moons around Saturn than Jupiter, Mr Sheppard said, given how much farther away Saturn is.

"So seeing that Saturn has more moons even though it is harder to find them, shows just how many moons Saturn has collected over time," he wrote in an email.

These smaller moons may have come from larger parent moons that broke apart right after Saturn formed.

Seventeen of Saturn's new moons orbit the planet in the opposite, or retrograde, direction.

The other three circle in the same direction that Saturn rotates.

They are so far from Saturn that it takes two to three years to complete a single orbit.

"These moons are the remnants of the objects that helped form the planets, so by studying them, we are learning about what the planets formed from," Mr Sheppard wrote.

Just last year, Mr Sheppard found 12 new moons around Jupiter.

The Carnegie Institution had a moon-naming contest for them and another is planned now for Saturn's new moons.

Monday's announcement came from the International Astronomical Union's Minor Planet Centre.

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