NEPTUNE ' s 14th MOON - S/2004 N 1

Diagram showing NEPTUNE' MOONS

This diagram shows the orbits of several Neptune moons. All of them were discovered in 1989 by NASA's Voyager 2 spacecraft, with the exception of S/2004 N 1, which was discovered in archival Hubble Space Telescope images taken from 2004 to 2009. 

The moons all follow prograde orbits and are nestled among Neptune's rings (not shown).

The outer moon Triton was discovered in 1846 — the same year the planet itself was discovered. Triton's orbit is retrograde, suggesting it is a captured Kuiper Belt object and therefore a distant cousin of Pluto. The inner moons may have formed after Triton's capture several billion years ago.

In the summer of 1989,  NASA's Voyager 2 spacecraft snapped a lot of pictures during its brief flyby over Nepturn. The prolific probe discovered several moons orbiting close to the blue-green planet.

While analyzing Neptune photos taken by the Hubble Space Telescope, astronomer Mark Showalter of the SETI Institute noticed an extra white dot about 65,400 miles from Neptune, located between the orbits of the moons Larissa and Proteus. 

This allowed him to plot a circular orbit for the moon, designated S/2004 N 1, which completes one revolution around Neptune every 23 hours. His discovery raises the number of known moons orbiting Neptune to 14.

Image Type: Illustration - Credit: NASA, ESA, and A. Feild (STScI)