Astronomers have found 12 more moons around Jupiter, and one is really weird. While 11 orbit in the same direction as their nearest neighbors, one doesn’t, potentially putting it on a fatal collision course.
“It’s driving down the highway on the wrong side of the road,” says planetary scientist Scott Sheppard of the Carnegie Institution for Science in Washington, D.C.
Sheppard and colleagues found the moons while looking for something else entirely: a putative planet that could exist beyond the orbit of Neptune, known colloquially as Planet Nine (SN: 7/23/16, p. 7). During a survey in 2017 of the most distant objects in the solar system using the Victor Blanco 4-meter telescope in Chile, Jupiter happened to be visible in the same area of sky that the team was searching during one of its observing runs. “Might as well kill two birds with one stone,” Sheppard thought.