That’s the newest tally of natural moons (if you’re keeping score) between the two most important planets in the solar system. Universe Today has the info on Scott Sheppard’s discoveries of the 66th and 67th moons of Jupiter. Temporarily designated S/2011 J1 and S/2011 J2, these 1-kilometer objects orbit Jupiter backwards (clockwise, as seen from “above”) and fairly far out from the planet. Can you imagine a month lasting 580 or 726 days? Imagine biological fertility based on a cycle like that.
Why are these moons important? For me, the big thing is curiosity. How in the heck do they get ensnared by a planet? Something passing by a planet has to slow down to get captured into an orbit. It doesn’t just happen because a rock decides it wants a home–though that would be an interesting speculation for a science fiction story.
Dr Sheppard tells it:
A planet has no known efficient mechanism to permanently capture satellites. Thus, outer satellite capture must have occurred near the time of planet formation when the Solar System was not as organized as it is now. The orbital history of a satellite can be very complex … but understanding where a satellite came from can tell us about the formation and evolution of our Solar System.
Will humans ever visit S/2011 J1 and S/2011 J2? Probably not. There are bigger and more interesting rocks in the asteroid belt. There are much bigger and more interesting moons closer to Jupiter.
Scott Sheppard is probably the number one moon hunter in astronomy today. He’s been involved with the detection of no less than 53 of the solar system’s known natural satellites. Check out his page for satellite count. When I was a kid, 31 known moons seemed like a lot. If you include dwarf planet Pluto (and exclude a growing number of asteroids and Kuiper Belt Objects), the count is now 176. Though that could change tomorrow.