Hubble Finds New Moon Orbiting Neptune
This composite Hubble Space Telescope picture shows the location of a newly discovered moon, designated S/2004 N 1, orbiting the giant planet Neptune, nearly 3 billion miles from Earth.
The moon is so small (no more than 12 miles across) and dim, it was missed by NASA's Voyager 2 spacecraft cameras when the probe flew by Neptune in 1989. Several other moons that were discovered by Voyager appear in this 2009 image, along with a circumplanetary structure known as ring arcs.
Mark Showalter of the SETI Institute discovered S/2004 N 1 in July 2013. He analyzed over 150 archival Neptune photographs taken by Hubble from 2004 to 2009. The same white dot appeared over and over again. He then plotted a circular orbit for the moon, which completes one revolution around Neptune every 23 hours.
The black-and-white image was taken in 2009 with Hubble's Wide Field Camera 3 in visible light. Hubble took the color inset of Neptune on August 19, 2009.