When it comes to the question of which planet has the most moons orbiting, Saturn has so far had the edge with 83 natural satellites. And this despite the fact that the gas planet with the iconic ring is only the second largest in our solar system. However, as a research group led by astronomer Scott Sheppard from the Carnegie Institution for Science recently discovered, twelve other previously unknown moons orbit Jupiter. This makes the largest planet now also the one with the most moons.
By 2021, 80 satellites were still counted around Jupiter, then there have been a dozen new discoveries in the past two years, which means that the gas giant is now orbited by 92 moons. The moons of Jupiter, which each take at least 340 days to orbit, were discovered with the help of telescopes stationed in Chile and Hawaii. Through follow-up observations, Sheppard and colleagues pinpointed the exact orbits and added the data to a list of all Jupiter moons maintained by the Minor Planet Center (MPC). Moon by moon, the MPC, part of the International Astronomical Union, confirmed the orbits, making the discoveries official.
There are two main reasons why the celestial bodies had previously remained hidden: On the one hand, the (as yet) unnamed moons – which are only assigned a name from a size of over 1.6 kilometers – are only between one and three kilometers in diameter. On the other hand, the sunlight reflected from Jupiter outshines that of tiny moons, which is why they are particularly difficult to see.
Where do all the moons around the giant planet come from?
However, this also means that it is highly probable that there will be other tiny moons orbiting both Jupiter and the other gas planets Saturn, Uranus and Neptune. In the moon ranking, Uranus is third with 27 moons behind Saturn. Neptune, which is furthest away from the sun, has 14 satellites. The stony planets Mars, Venus, Earth and Mercury, which are close to the sun, are far behind in the lower ranks. Mars still has two moons, while Venus and Mercury have none.
However, it is still unclear which processes have given Jupiter its moon wealth. Astrophysicists suspect that the many small moons are remnants of larger celestial bodies that once collided with each other or with passing comets or asteroids. Like most of the outer moons, the newly discovered natural satellites then likely got caught in the gravitational pull of 318 Earth-mass Jupiter. “I hope we can get a close-up of one of these outer moons in the near future to better determine their origin,” Sheppard told the science portal Phys.org.
The space probe is also intended to provide new insights into Jupiter’s moons juice (Jupiter Icy Moons Explorer) which is scheduled to launch on April 5th. The probe of the European Space Agency Esa will focus on the moons Europa, Ganymede and Callisto discovered by Galileo Galilei in 1610. With the exception of volcanic Io, those three of the four Galilean moons are covered by an icy crust beneath the surface of which there may be an ocean of liquid water. Esa researchers were particularly impressed by Ganymede – and the question of whether one of the moons could offer life-friendly conditions. However, you will still have to be patient for measurement data. It will take nearly eight years for Juice to enter Ganymede’s orbit.