Jupiter Officially Has 12 New Moons

James Marshall
July 19, 2018

A dozen new moons have been discovered around Jupiter, bringing its total number of known moons to 79, the most of any planet in our solar system, astronomers announced Tuesday.

The moons were first discovered during the search for Planet X, the hunt for a massive planet beyond Pluto. They take a little less than a year to orbit the gas giant. Its powerful gravitational pull allows it to capture large passing objects that then collide with each other, forming dozens of new, smaller moons. As so often happens, the astronomers found the moons while searching for something completely unrelated.

Most of the newly discovered moons orbit opposite to Jupiter's spin, what's known as a retrograde orbit.

Valetudo is the smallest of the moons discovered, likely just under a kilometer wide (the size isn't measured directly - it's too small - but estimated from its brightness). Until the announcement this morning by the International Astronomical Union of the discovery of an additional 10 moons about the gas-giant planet.

Astronomers have found 12 previously unknown moons circling Jupiter, including one "oddball" whose days are numbered, due to its highly unusual orbit. Because they formed between the two belts, the moons are probably composed of rock and ice. They are thought to be the remnants of larger parent bodies that were broken apart in collisions with asteroids, comets and other moons.

Jupiter's 79 moons make it the most orbited planet in the Solar System.

Another two orbs were spotted among the inner group of moons, which orbit in the prograde (same direction), and take slightly less than a year to travel around Jupiter. The moon can be seen moving relative to the steady state background of distant stars. The largest among them are the Galilean satellites-Io, Europa, Ganymede, and Callisto-large moons that orbit close to the planet.

The black-sheep moon boasts a 1.5-year orbit that, unfortunately for big-shot Jupiter, crosses the outer retrograde planetoids-a cosmic recipe for destruction.

"It's basically driving down the highway in the wrong direction", Sheppard said.

Astronomers suspect that the retrograde moons may be the remains of larger moons that were destroyed in head-on collisions with prograde objects.

Eleven of the new moons join existing groups of Jovian satellites, but one of Jupiter's new moons follows a unique, odd path.

In fact, Sheppard and his team at Carnegie think that this moon could be all that's left of a previous collision in orbit around Jupiter. The researchers proposed naming the unique find Valetudo after the Roman god Jupiter's great-grandaughter.

The Cerro-Tololo Inter-American Observatory in Chile is "magnificently desolate", according to astronomer Scott Sheppard.

Telescopes in Chile, Hawaii and Arizona were used for the latest discovery and confirmation. With orbital periods of about one year, they also are thought to be the result of earlier collisions. "So understanding these moons helps us understand what the planets were originally made from". We already have a classification for dwarf planets.

Over the weeks following full opposition, Jupiter will reach its highest point in the sky four minutes earlier each night, appearing as a bright, star-like object.

It will appear as the fourth brightest object in the sky behind the moon, Mars and Venus.

Other reports by Click Lancashire

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