spacetoday.net: Neptunian moon recovered in Hubble images

Posted: Wed, Oct 9, 2013, 7:25 AM ET (1125 GMT)
Nereid and Neptune (SETI Inst.)

A tiny moon of Neptune not seen since its discovery by Voyager 2 nearly a quarter-century ago has been found by astronomers examining Hubble images, but in an unexpected location. Astronomers analyzed archival images of Hubble in an effort to detect the planet's small innermost moon, Nereid, not seen since it was discovered in images taked by Voyager 2 during its flyby of Neptune in 1989. They were able to find it in eight images of Neptune taken in 2004, using new techniques to surpress the glare from Neptune that made the moon hard to see. The moon, though, was far ahead of its predicted position based on the orbit calculated from its 1989 discovery, leading astronomers to speculate it may have been subject to unforeseen gravitational interactions with other moons.