Physics-Astronomy.org

For the first time in decades, a new tiny moon has been found in orbit around the gas giant Neptune, according to a study published Wednesday in the journal Nature. Hippocamp, now known as Neptune's smallest moon, is named for the sea monster from Greek mythology, said to have a fish's tail attached to a horse's body. It's only about 21 miles in diameter; by comparison, Neptune is 30,599 miles in diameter.

This latest discovery was made by Mark Showalter, a senior research scientist at the SETI Institute, and his team, using observations from the Hubble Space Telescope.

The Voyager 2 spacecraft conducted a flyby of Neptune in 1989 and spotted six small inner moons -- but not Hippocamp. This makes Hippocamp the seventh inner moon found around Neptune, bringing the planet's total moons to 14.

Hippocamp is in close orbit to Proteus, the largest and outermost of Neptune's inner moons. And the researchers believe that Hippocamp is a fragment of Proteus.

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