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Illustration showing the newly discovered moon (in bold). Image via Carnegie Science / Roberto Molar Candanosa
Our solar system is full of moons of different kinds, as diverse and astonishing as the planets they orbit. While the Earth has only one moon, and some planets, like Mercury and Venus, do not have one, others have dozens, namely Jupiter and Saturn. . Ice giants Uranus and Neptune also have some of them. On July 17, 2018, astronomers announced they had discovered even more moons in orbit around Jupiter – an additional 10 moons, bringing the known total of Jupiter's moons to 79. Nine of those 10 moons are what astronomers call normal but they labeled it as a real weird . As often happens, astronomers have found moons looking for something totally different.
These astronomers said that they came on the new moons looking in the outer solar system for the evidence of the planet Nine, a great planet still invisible. by some scientists to exist in the farthest parts of the solar system, far beyond Pluto. It was in the spring of 2017. Scott S. Sheppard of the Carnegie Institute for Science led the astronomy team. He said that Jupiter was near the research field where they were looking for Planet Nine, and he added:
Jupiter was in the sky near the search fields where we were looking for extremely distant solar system objects, so we were able to search for new moons around Jupiter while searching for planets on the periphery of our solar system.
Images of the Moon oddball – now called Valetudo – from the Magellan Chile telescope in May 2018. Image via Carnegie Science
Why are we now hearing about it? These astronomers said that even though the new sightings were exciting, they needed to confirm them. As Gareth Williams explained to the Minor Planet Center of the International Astronomical Union:
It takes several observations to confirm that an object is in orbit around Jupiter. Thus, the whole process took a year
It should be noted that the July 17 announcement by Carnegie Science also contains two moons that had been previously found and announced in 2017. These moons of 2017 have been labeled S / 2016 J1 and S / 2017 J1. This gives us a total of 12 new moons for Jupiter confirmed since early 2017, two last year and 10 this year.
All these new moons are very small, only about one to three kilometers wide (one kilometer is 0.6 miles). In this way, they are like many other small moons of Jupiter. They are thought to have formed after the gas and dust of the early stages of planetary formation dissipated.
Nine of the 10 new moons orbit in a retrograde direction, that is to say in the opposite direction of the Jupiter spin. They are part of a larger swarm of moons orbiting around a long distance of Jupiter. It is thought that all these moons are the remains of three much larger bodies that were destroyed by collisions with other moons, asteroids or comets.
The 10th New Moon is . It is farther away than the prograde moons of Jupiter – those that turn in the same direction as the spin of Jupiter – and its orbit is much more inclined, crossing the orbits of the outer retrograde moons. He was nicknamed Valetudo, after the great-granddaughter of the Roman god Jupiter. According to Sheppard:
Our other discovery is a real eccentric ball and has an orbit like no other known Jovian moon. It is probably the smallest known moon of Jupiter, having less than one kilometer in diameter
Since Valetudo moves in the opposite direction to the other retrograde moons, there is more chance that it will not be possible. a collision occurs. inevitable. As Sheppard noted:
This is an unstable situation. The frontal collisions would break quickly and reduce the objects to dust.
At Inverse.com, Sheppard also offered an earthbound analogy saying that:
He actually goes head-to-head on these retrograde objects. It would be like driving a road in the wrong direction
Such collisions would have been very common earlier in the history of Jupiter, while most moons were still forming from the gas and dust surrounding the young planet. are the 4 largest Galilean moons of Jupiter – Callisto, Europa, Io and Ganymede, which can be easily seen from Earth. Image via NASA. Read More: How to See the Moons of Jupiter
The other two moons mentioned by Carnegie Science are much closer to Jupiter, and orbit in the prograde direction, in the same direction as Jupiter's rotation. They are also part of a larger group of smaller moons that are believed to be the remains of a formerly larger moon.
We still find moons for Jupiter. As to how much will finally be found, no one knows for sure. For a long time, the number hovered at 69, and now it is 79. It is likely that other small moons are still waiting to be found. According to Sheppard:
Well, it will probably not stay at 79 very long. In fact, we discovered that on some of our best nights we could shoot even deeper objects – things that are at the limit of noise. There are many more smaller moons around Jupiter. It's just very difficult to follow those.
Bottom line: For a long time, Jupiter had been known to have dozens of moons. Now, thanks to a research that was primarily for Planet Nine, astronomers have discovered even more – 79 in total. It is the largest number of moons of any planet in the solar system
Via Carnegie Institute for Science
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