Astronomers this week announced that Neptune's small inner moon, named Naiad, has been spotted for the first time since the Voyager 2 probe left Neptune's orbit in 1989. Researchers led by SETI scientist Mark Showalter found the moon in images taken by the Hubble Space Telescope in December 2004.
“Naiad has been an elusive target ever since Voyager left the Neptune system,” said Showalter.
Showalter and his colleagues developed new techniques to see through the glare cause by Neptune in the images. The planet is, according to SETI, 2 million times brighter than Naiad. In addition to the moon, the revealed images also show Neptune's many rings and ring-arcs, as well as several of its other inner moons, including Galatea, Larissa, and Proteus.
Also shown is the recently-discovered moon currently designated as S/2004 N 1. That moon was discovered earlier this year by Showalter and his team.
“It is always exciting to find new results in old data," said Showalter. "We keep discovering new ways to push the limit of what information can be gleaned from Hubble's vast collection of planetary images.”
Oddly, Naiad was not where astronomers expected it to be in the images. The moon was found to be "significantly off course" from its predicted location based on Voyager's observations. New research will be needed to determine why this is the case, though researchers currently suspect that gravitational interactions between Naiad and other nearby moons may be the most likely cause.