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The Hubble Telescope Just Discovered Neptune's Smallest Moon

Photos from the Hubble Space Telescope have revealed a previously unknown moon spinning around distant Neptune.

The Hubble Telescope Just Discovered Neptune's Smallest Moon

Somewhere in the dim and dark void about 65,000 miles above the blue clouds of Neptune there's a little moon, just 12 miles across, that orbits its home about once every Earth day. It's Neptune's smallest known moon, and it's been there for eons, but we've only just discovered it! Neptune is now known to have 14 natural satellites.

The new moon, sexily dubbed S/2004 N1, is so very tiny and very dim that it's escaped detection until now. Even Voyager 2, NASA's landmark space exploration vehicle, missed it while racing through the Neptunian system in 1989, close enough to snap detailed pictures of Neptune's most famous moon, Triton.

S/2004 N1 was found during analysis of about 150 archived photos taken by the Hubble Space Telescope. Mark Showalter of the SETI institute was looking at Neptune's ring arcs—which are like smaller, incomplete versions of Saturn's rings.