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Astronomers discover 12 more moons orbiting Jupiter, including an 'oddball'

The solar system's largest planet has some "new" neighbors.

Astronomers have discovered 12 additional moons orbiting Jupiter, bringing the total to 79, the most of any planet in the solar system, a new study found.

The moons were discovered while astronomers were searching for objects at the edge of the solar system, according to Scott Sheppard, a scientist at the Carnegie Institution for Science who co-authored the study.

“Jupiter just happened to be in the sky near the search fields where we were looking for extremely distant solar system objects, so we were serendipitously able to look for new moons around Jupiter while at the same time looking for planets at the fringes of our solar system,” Sheppard said.

One of the objects they were looking for is the mysterious "Planet X" or "Planet Nine," which remains undiscovered.

The discovery of the new moons was reported Tuesday in the Minor Planet Electronic Circular, a publication of the International Astronomical Union.

Researchers say the new Jupiter moons weren’t seen before because they are tiny – the biggest ones are only about two miles across.

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One of the newly discovered moons is an "oddball," Sheppard said. "It has an orbit like no other known Jovian moon,” he explained. It orbits in an opposite direction from the other moons near it, meaning head-on collisions are much more likely to occur.

“This is an unstable situation,” said Sheppard. “Head-on collisions would quickly break apart and grind the objects down to dust.

“It’s also likely Jupiter’s smallest known moon, being less than one kilometer (0.6 mile) in diameter."

Telescopes in Chile, Hawaii and Arizona were used for the original discovery and year-long confirmation of the moons.

“It takes several observations to confirm an object actually orbits around Jupiter,” said Gareth Williams of the International Astronomical Union’s Minor Planet Center. “So, the whole process took a year.”

Legendary Italian scientist Galileo first detected Jupiter’s four largest moons, Io, Europa, Ganymede and Callisto in 1610.

Contributing: The Associated Press