NASA's Hubble Telescope has made a new discovery about Neptune, the eighth and farthest planet from the sun in our solar system now that Pluto doesn't count anymore. While studying the segments of rings around Neptune, Mark Showalter of the SETI Institute in Mountain View, Calif., decided to broaden his view. "We had been processing the data for quite some time and it was on a whim that I said, ‘OK, let's just look out further," Showalter told Reuters. "I changed my program so that instead of stopping just outside the ring system it processed the data all the way out, walked away from my computer and waited an hour while it did all the processing for me. When I came back, I looked at the image and there was this extra dot that wasn't supposed to be there," Showalter said.
Showalter began to track the movement of the dot in more than 150 archived photographs taken of Neptune by Hubble from 2004 to 2009. Using this method, he plotted a circular orbit for this moon, which completes one revolution around Neptune every 23 hours. "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," Showalter said. "It's the same reason a sports photographer tracks a running athlete: the athlete stays in focus, but the background blurs."
Neptune's new and 14th moon, unsexily designated "S/2004 N1," is estimated to be only about 12 miles across. It's so tiny that it's about 100 million times fainter than the faintest star that can be seen with the naked eye. This small moon even escaped detection when NASA's Voyager 2 spacecraft flew past Neptune in 1989 to survey the planet's system of moons and rings. The new moon is about 65,400 miles from the planet and is located between the orbits of Larissa and Proteus, two of Neptune's other moons.