Jupiter, the bully of the solar system, keeps a constant barrage of surprises popping out of her system of moons. Now she’s caught up with Saturn.
Cosmologists and astronomers recently released a new model of our early solar system that has Jupiter and Saturn wildly careening through a variety of orbits. In theory the two gas giants roared in towards the sun on a vane of gas, terrorizing the then-developing rocky planet Mars. The gas ran out before Jupiter was swallowed up by the sun, but her path through the inner solar system may have messed everything up, orbitally speaking.
There is theorized to have been a pretty vast field of rocky matter adrift around the then-developing sun. Mercury, Venus, Earth and Mars were all forming at roughly the same time from this disk of orbiting loose rock. Jupiter’s untimely arrival interrupted Mars’ development and shoved her share of rocks out into the asteroid belt. Saturn pulled Jupiter back into space to, or very close to, her current orbit, but the damage was done. Mars was left anemic and the asteroid belt was formed.
But Jupiter appears to have done a little bit more than merely spin the rocks of that early accretion disk away into the asteroid belt. She picked up quite a few as her own moons. In fact, the current count is 64.
Some of Jupiter’s moons, like Io, Europa, and Ganymede, are big enough to be planets themselves and may very well be composed of the matter that would otherwise have gone into Mars. Each of these moons is a wild and exotic place, filled with planet-like idiosyncrasies.
The bulk of Jupiter’s moons, however, are tiny fragments of rock and ice that were probably snapped out of that early accretion disk. If they are, they are among the most ancient objects in the solar system.
These last two moons to be discovered are tiny. They bear the romantic names S/2010-J1 and S/2010-J2. The nomenclature shows that they are (S)atellites discovered in 2010 around (J)upiter, the 1st and 2nd to be discovered in that year. These two, spotted by ground-based telescopes in California, stand in line behind the 23 moons discovered by the Galileo spacecraft in 2003. Their discovery brings the number of moons orbiting Jupiter up to 64, the same number as those orbiting Saturn – the other half of the early-solar-system-Mars-wrecking duo.
But these are tiny bodies – so small no photograph yet exists of them. They may have been culled out of the proto-planetary accretion disk, pulled out of the asteroid belt much later, or even could be captures of in-falling matter from much farther out. Whatever they, they now belong to Jupiter.