New research suggests the moons of Jupiter and Uranus may hint that our planetary neighborhood once had a third ice giant.

Editor's note: This article was updated March 25 at 11:40 a.m. ET to account for the recent discovery of new moons around Saturn and Jupiter. The total number of planetary moons and small-body ...

Neptune has a complicated life story, and its moon Nereid might be the only one left standing from the planet’s ...

Neptune’s third-largest moon, Nereid, could be an intact survivor from the planet’s original satellite system, upending ...

Neptune’s far-flung moon Nereid may be the last of the planet’s original companions that managed to survive a cosmic crash, ...

The outer planets of the solar system are swarmed by ice-wrapped moons. Some of these, such as Saturn's moon Enceladus, are known to have oceans of liquid water between the ice shell and the rocky ...

Nereid was discovered by Dutch astronomer Gerard Kuiper, who named the moon after the sea nymphs in Greek mythology ...