Jupiter’s New Moons

Steph P. Bianchini July 25, 2018 10 Comments

If you thought (like me) that Jupiter only had 65 moons, get ready to be surprised: according to NASA, there are (at least) 12 more lining up and awaiting a name. 11 of them are “normal” outer moons, plus one, the twelfth, that the scientist called an “oddball.”  With this moon count, Jupiter reaches 79 —more than any other planet in our Solar System.

The discovery is actually of last year, but it took one year of observations to confirm it. “A team led by Carnegie’s Scott S. Sheppard first spotted the moons in the spring of 2017 while they were looking for very distant Solar System objects as part of the hunt for a possible massive planet far beyond Pluto.  In 2014, this same team found the object with the most-distant known orbit in our Solar System and was the first to realize that an unknown massive planet at the fringes of our Solar System, far beyond Pluto, could explain the similarity of the orbits of several small extremely distant objects. This putative planet is now sometimes popularly called Planet X or Planet Nine.  University of Hawaii’s Dave Tholen and Northern Arizona University’s Chad Trujillo are also part of the planet search team. 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.” (Read the whole story here).

The oddball moon is the most interesting. It has an orbit like no other known Jovian moon, together with being the smallest one, less than one kilometre in diameter. It is more distant than the others just discovered, more inclined, and it takes about one and a half years to orbit Jupiter. As a result, the oddball moon has an orbit that crosses the outer moons. In situations like these, “head-on collisions are much more likely to occur between the ‘oddball’ prograde and the retrograde moons, which are moving in opposite directions.”

Fascinating, isn’t it? This video explains more.