The moons of Jupiter: astronomers find 10 more, including a ball named Valetudo

Jupiter is often described as a miniature solar system. The gaseous giant is made from the same basic ingredients as the sun – hydrogen and helium – and is surrounded by a series of geologically diverse moons.

Today, the Jupiter system becomes even more impressive. The International Astronomical Union has confirmed the discovery of 10 new moons, bringing the total to 79. This discovery includes a very strange moon that helps explain why there are so many others.

Where did these moons go all this time?

How can 10 moons go unnoticed?

The short answer: These moons are relatively tiny, a few miles away or more. And even with high power telescopes, it can be very difficult to spot small dark objects next to something as massive and bright as Jupiter.

"As our technology improves, we are weaker and we discover ever smaller moons," said Scott S. Sheppard, astronomer of the Carnegie Institution for Science.

These new moons were discovered using a 520-megapixel camera attached to the huge Victor M. Blanco telescope in Chile. (For reference: The latest iPhone has a 12-megapixel camera.) The camera not only has a dense resolution, but it is also specially calibrated to find faint objects.

Also, Jupiter's gravity is so strong that she can keep objects in orbit up to 18.6 million miles. (Remember that our moon is only 239,000 miles away.) This means that there is a lot of space around Jupiter for astronomers to examine moons.

How to Discover Moons of Jupiter

Sheppard and his team were not in fact, they were looking for new moons when they discovered them – they were looking for other distant and difficult objects to spot in front of Pluto.

When their telescope sweeps the sky, it takes objects at all distances. It can detect stars at millions of light-years away. He can spot objects from the Kuiper belt near the edge of the solar system. And he can see objects closer to the house, like the eight planets. All of these objects could be in the same picture.

It's the movement of these objects over a period of time that tells astronomers what and where they are. "It's like when you drive in your car," says Sheppard. "When you look at the side of the road, traffic signs fly very fast while driving, and the mountains in the background are moving very slowly." The slowest objects are farther away. And if an object moves at the same speed as Jupiter, it is likely that it is in the same place.

The team first noticed the moons in 2017, but they needed a year of follow – up observations to trace the shape of their orbits and confirm that they were not. they were not really asteroids or comets orbiting the sun.

This is what the telescope actually captured. Most of the white dots in the photo are stars. But you can see a moon, marked with orange lines on each side, moving so slightly from one frame to the other. It was the big clue that it was a moon of Jupiter. He was moving against a background of static stars.

Carnegie Institution for Science

Humans have discovered moons of Jupiter since Galileo spotted the first four great – Callisto, Io, Europa and Ganymede – in 1610.

This is not really a shock that we are still discovering them, considering that our telescopes become more and more capable of distinguishing the weakest objects. Two moons were announced last year. And Sheppard suspects that there is even more to find.

Only one of the moons has a name for the moment. Presentation of Valetudo.

Nine of the moons remain nameless (for the moment). But a special has been named.

He is called Valetudo, named after the Roman goddess of health and hygiene. The new moons of Jupiter are named after the Roman gods linked to Jupiter. Valetudo is the great-granddaughter of Jupiter. And adorably, Sheppard chose Valetudo as a nod to his girlfriend, whom he describes as a "very clean person."

Carnegie Institution for Science

Moons close to Jupiter tend to orbit in a "prograde" movement, which means the same direction as the rotation of Jupiter. Those who are farther away are turning in a retrograde motion. But Valetudo is a strange duck. It is in orbit in a prograde movement in the retrograde region.

"It's like driving on the highway in the wrong way," Sheppard says. "It revolves around Jupiter in one direction, and there are, like objects of something that revolve around Jupiter in the other direction." This means "most likely to have some kind of frontal collision," says he.

And it's actually an important clue to why there are so many moons around Jupiter. Sheppard explains that a long time ago, there were probably fewer larger moons in orbit around Jupiter in this retrograde region. But over time, they were broken into pieces.

It is possible that Valetudo – or a previous larger version – was the destructive force behind the collision. Imagine the chaos that would ensue if a semi-trailer rolled against traffic on a highway; it's Valetudo. "It gives us all this swarm of things we see today," Sheppard says.

There are still many unknown things about these moons, like what exactly they look like or what they are made of. NASA's Juno spacecraft, currently orbited around Jupiter, is not able to image them. It will take a future mission to Jupiter to have a clearer vision of the moons. The only things we know about them are their approximate sizes and shape of their orbits.

But if we study them more deeply, they could also reveal clues about the origin of our solar system. The outer planets – Jupiter, Saturn, Uranus, Neptune – were formed by sucking smaller objects in their paths. And the objects that were not consumed were captured in their orbits.

"These outer moons," says Sheppard, "are like the last vestiges of the planetesimals, the first objects that formed our solar system."

Further reading: Jupiter, the King of the Planets