Astronomers Spot 12 New Moons Around Jupiter — And One Is Particularly Weird

The hunt for Planet Nine is turning up all sorts of strange discoveries, just like the mysterious rocky object in the Kuiper Belt the Inquisitr reported on earlier this year. In this particular case, astronomers looking for the elusive Planet X beyond Pluto ended up finding an extra set of moons around Jupiter, Science Daily reports.

Last spring, the scientists were scouring the sky with the Blanco 4-meter telescope at the Cerro Tololo Inter-American Observatory in Chile and Jupiter popped in their view, said team leader Scott Sheppard, an astronomer with the Carnegie Institution for Science.

“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 pointed out.

The observations revealed a dozen previously unknown moons circling the gas giant. These newfound objects are tiny, ranging between one and four kilometers in diameter (0.6 to 2.5 miles), and have been officially confirmed as moons about a year after their discovery, once the astronomers tracking their orbit were sure of what they had found.

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

This latest discovery brings the total number of Jovian moons to 79, making Jupiter the planet with the largest number of moons in the solar system.

Prograde Jovian Moons

Two of the newly-discovered Jovian moons belong to an inner group called prograde moons, which spin in the same direction as Jupiter, explains a news release by the Carnegie Institution for Science.

These prograde moons lie a bit farther away than Jupiter’s four large Galilean moons, Io, Europa, Ganymede, and Callisto, notes Gizmodo, and are believed to be the surviving fragments of a larger moon that got torn apart by collisions with other celestial bodies, such as asteroids, comets, and even similar moons, in the planet’s distant past.

Until now, there were only four known prograde moons orbiting Jupiter. These two newfound prograde moons, which take a little less than a year to complete a full orbit around the gas giant, raise the number up to six.

Retrograde Jovian Moons

Nine of the recently spotted moons fall into a separate category called retrograde moons. Previously believed to hold just 61 objects, this group circles the planet in the opposite direction of Jupiter’s rotation and is even more distant than the prograde moons.

Jupiter’s retrograde moons are thought to have spawned from three larger bodies which were destroyed during past violent collisions. This is because these outer moons are huddled together in three orbital groupings, which point to three separate origin sources.

The nine retrograde moons recently found in Jupiter’s orbit go around the planet in roughly two years. According to Gizmodo, two of them had already been announced by the team in 2017, when the world found out that Jupiter had 69 moons.

The ‘Oddball’

The remaining Jovian moon has been labeled an oddity, and here’s why.

“Our other discovery is a real oddball and has an orbit like no other known Jovian moon,” Sheppard stated. “It’s also likely Jupiter’s smallest known moon, being less than one kilometer in diameter.”

This curious newfound moon spins in the same direction as the prograde and the Galilean moons, following Jupiter’s rotation, but it’s so far away from the planet that it actually takes up residence among the retrograde moons.

Because it travels in the complete opposite direction as the rest of the neighborhood, this tiny moon is particularly vulnerable to collisions and stands a good chance of being obliterated in the future by an impact with a retrograde moon.

“It’s like driving a car on the wrong side of the highway,” Sheppard said in a statement.

Dubbed Valetudo, after the goddess of health and hygiene, great-granddaughter of the Roman god Jupiter, this peculiar object orbits the planet in a year and a half and seems to have an intriguing history.

Unlike the other Jovian moons that broke apart soon after the planet was formed, Valetudo is believed to be the remnant of a foreign celestial body. This strange moon could have come from a stray comet trapped by Jupiter’s gravitational pull and destroyed long ago by collisions with the planet’s retrograde moons.

“This just shows how chaotic our solar system was in the past. These outer moons of Jupiter are remnants of chaos,” Sheppard said.