WASHINGTON -- NASA's Hubble Space Telescope has discovered a fourteenth moon orbiting Neptune.
The moon, called S/2004 N 1, was discovered by Mark Showalter of the SETI Institute in Mountain View, Calif. on July 1, while he was studying the faint arcs, or segments of rings, around Neptune.
His began tracking the movement of a white dot that appeared over and over again in more than 150 archival Neptune photographs taken by Hubble from 2004 to 2009.
S/2004 N 1is estimated to be no more than 12 miles across, making it the smallest known moon in the Neptunian system. According to NASA, it is so small and dim that it is roughly 100 million times fainter than the faintest star that can be seen with the naked eye, which is why is was only recently discovered. It escaped detection by NASA's Voyager 2 spacecraft, which flew past Neptune in 1989 and surveyed the planet's system of moons and rings.
"The moons and arcs orbit very quickly, so we had to devise a way to follow their motion in order to bring out the details of the system," said Showalter. "It's the same reason a sports photographer tracks a running athlete -- the athlete stays in focus, but the background blurs."
The moon is about 65,400 miles from Neptune, located between the orbits of the Neptunian moons Larissa and Proteus. Showalter plotted a circular orbit for the moon, which completes one revolution around Neptune every 23 hours.
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