Which is more shocking: the fact that Jupiter has at least 12 more moons than once thought or the fact that they were discovered by real astronomers who were looking for the mythical Planet Nine? Planetary scientists announced that the discovery of the tiny and somewhat erratic moons brings Jupiter’s total to 79, but are they just bragging to cover up the time they spent searching for an allegedly apocalyptic yet unproven giant planet?
“Jupiter just happened to be in the sky near the search fields where we were looking for extremely distant Solar System objects, so we were serendipitously able to look for new moons around Jupiter while at the same time looking for planets at the fringes of our Solar System.”
In a press release by The Carnegie Institution for Science, part of the Carnegie Institution of Washington, astronomer Scott S. Sheppard admitted publicly that he and his team were looking for Planet Nine or Planet X in 2017 when Jupiter passed into the field of vision of their telescopes and they spotted the 12 tiny new moons. “Tiny” is an overstatement – most the moons range from just one to three miles in diameter. It required waiting a year for them to appear a few more times before the team was confident enough to announce the find.
Nine of the newly discovered moons are in three groups making distant retrograde orbits (opposite Jupiter’s rotation) and the researchers speculate they may be what’s left of three larger moons that suffered collisions with each other, other moons, asteroids or comets. Two more moons are closer to Jupiter and follow its spin. Their matching orbits and tilts indicate they were probably once a single moon.
Then there’s the tiny eccentric satellite.
“Our other discovery is a real oddball and has an orbit like no other known Jovian moon. It’s also likely Jupiter’s smallest known moon, being less than one kilometer in diameter. This is an unstable situation.”
According to Sheppard, this moon’s orbit is prograde despite being far enough from Jupiter that it should be retrograde or at least off-kilter due to collisions. The abundance of these tiny moons suggests that they formed after the solar system’s planetary creation had settled down, allowing them to survive rather than be knocked down by Jupiter’s formational gas and dust.