New Moons


LUNAR ORBITS: This diagram shows the paths of Jupiter’s 79 moons. They revolve around the gas giant in three distinct groups—the Galilean moons, the prograde group, and the retrograde group.

Jupiter has long held the record for having the most moons of any planet in our solar system. Now, 12 more moons have been discovered. That brings the number of natural satellites orbiting, or revolving around, the gas giant to 79.

One of the newly discovered moons, nicknamed Valetudo, is particularly strange. That’s because it’s orbiting Jupiter in a direction opposite to the orbits of nearby moons. Valetudo’s odd orbit poses a serious collision hazard for its neighbors. In fact, scientists believe Valetudo may be the remnant of a large moon that broke apart after multiple impacts with some of Jupiter’s other moons. Another hit could reduce its size even further.

Scott Sheppard is an astronomer at the Carnegie Institution for Science in Washington, D.C. He led the team that discovered the new moons. “Collisions occur every billion years or so,” he says. “That’s long in human lifetimes, but not long for the life of the solar system.”