NASA this week revealed that a new moon has been spotted orbiting the furthest planet from the sun, Neptune.

The moon, the 14th known to be orbiting Neptune, has been labeled S/2004 N 1. The small rock is the smallest of Neptune’s known moons at approximately 12 miles across. It is located around 65,400 miles from Neptune, between the orbits of Neptune moons Larissa and Proteus, and orbits Neptune once every 23 hours.

The moon is so small that it was missed by the Voyager 2 probe when it surveyed Neptune in 1989. It was spotted by the Hubble telescope in pictures taken from 2004 to 2009, but also went unnoticed until this month. Mark Showalter, an Astronomer at the SETI Institute in California, was studying the ring segments around Neptune when he “on a whim” extended his analysis beyond Neptune’s ring system. He spotted a small white dot, S/2004 N 1, which he was then able to find in 150 archival Hubble Space Telescope photos to plot its orbit.

“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.”