Twenty newly discovered moons orbiting Saturn fit into three groupings of previously known satellites. Saturn’s total of 82 known moons is a new solar system record. Image: NASA/JPL-Caltech/Space Science Institute (Saturn), Paolo Sartorio/Shutterstock (background stars)
A team led by Carnegie astronomer Scott Sheppard has discovered 20 new moons orbiting Saturn, pushing the ringed planet’s total to a record 82 – three more than Jupiter’s currently known 79.
Each of the newly discovered moons has a diameter of about five kilometres (3 miles) and 17 of them orbit Saturn in the a retrograde direction opposite the planet’s rotation. The other three orbit in the same prograde direction as Saturn.
The retrograde moons orbit at roughly the same inclination, or tilt, indicating they may be fragments of a larger body that broke apart in the distant past. Likewise, two of the newly found prograde moons fit in with an already known group sharing an orbital tilt of about 46 degrees. They, too, may have once been part of a larger moon.
The third newly found prograde moon orbits at an inclination of 36 degrees, similar to a group of inner prograde satellites. This one, however, is much farther from Saturn than any ...