Twelve new moons have been identified around Jupiter, including Valetudo the "eccentric" – Sciences

Nelly Lesage –
             at the Moment
– Science

Astronomers have discovered the presence of twelve additional satellites around Jupiter. Among these moons, a star stands out: Valetudo, who risks colliding with his sisters.

Has Jupiter ever revealed all its mysteries? The oldest planet in the solar system is still the focus of astronomers' attention: on 16 July 2018, a team from the Carnegie Institution in Washington (a scientific research foundation, one of whose research focuses on astronomy) announced that a dozen moons had been discovered around the planet.

If the discovery is in itself significant, the surprise does not stop there : astronomers count " a dozen "moons, one of which quiserait somewhat" eccentric "(they speak of a" oddball "). These newly identified celestial objects would-baduming that the last is a moon-would be the total number of known moons of Jupiter at 79.

79 moons around Jupiter: a new record for the granny of the solar system

This would of the planet the new holder of a record in our solar system, because no other can boast of possessing as much (in any case, not to the knowledge of human beings.)

These new moons have been identified by Scott Sheppard, a member of the Department of Earth Magnetism at the Carnegie Institution in Washington. He and his team spotted the moons for the first time in 2017, as they watched objects from the solar system far and wide, looking for a planet further than Pluto. However, Jupiter was close to their field of research.

Lighter and farther than their sisters

Compared to the satellites that Galileo had identified around Jupiter in 1610 – Io, Europe, Ganymede and Callisto – the new moons observed by astronomers are much lighter. They measure between one half mile and two miles between 800 meters and 3 kilometers in width. These twelve stars are in orbit millions of kilometers from Jupiter. These two characteristics make it possible to understand why the moons had never been seen before.

Two of these moons are in orbit, rather close to Jupiter, and move in the same direction as that of the rotation of the planet. Nine other satellites turn in the opposite direction, about 25 million kilometers from Jupiter (15.5 million miles). It is in this area that is also Valetudo the moon described as " eccentric ": indeed, it turns in the same direction as the first two moons close to Jupiter.

In other words, Valetudo moves in the opposite direction of all the moons that are close to its orbit. " It's like driving on a highway in the wrong direction Scott Sheppard has fun with The Verge. This is a very unstable situation. Frontal collisions are likely to occur in this situation. "

This situation is not unique around Jupiter: another moon on the planet, called Carpo, also moves in the opposite direction to other satellites that are close to it. Nevertheless, the orbit of Valetudo is much farther away than that of Carpo. Moreover, astronomers believe that Valetudo could be the smallest moon of Jupiter.

Valetudo "drives a highway in the wrong direction"

The discovery thus invites astronomers to postulate that collisions between moons have occurred in the past of Jupiter. These events could even explain why so many moons are in orbit around Jupiter today. " Valetudo, with a diameter of only one kilometer, is probably the last remnant of a much larger moon which has been reduced to dust over time ," postulates Scott Sheppard.