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S/2004 N1: Overview
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S/2004 N1 within the Neptune system
This composite Hubble Space Telescope picture shows the location of a newly discovered moon, designated S/2004 N1, orbiting the giant planet Neptune, nearly 3 billion miles from Earth.

Initial astrometry indicates that S/2004 N1 travels in a near-circular, uninclined orbit and has a mean radius of about 8-10 km, assuming an albedo of 0.01. This makes S/2004 N1 much smaller than any of Neptune's previously known satellites, and below the detection threshold of the Voyager cameras sent there in 1989. S/2004 N1 is so small and dim that it is roughly 100 million times fainter than the faintest star that can be seen with the naked eye.

S/2004 N1 orbits its parent planet Neptune every 23 hours. The projected radial distance from the parent planet's center is 105,300 +/- 500 km. This places the satellite between the orbits of two other moons of Neptune: Larissa and Proteus.

Discovery:
S/2004 N1 was discovered by Mark Showalter on 1 July 2013 using Hubble Space Telescope (HST) images taken of the Neptune system between 2004 and 2009. Showalter analyzed over 150 archival photographs of the system in which the same white dot appeared over and over again. He then plotted a circular orbit for the moon.

How S/2004 N1 Got its Name:
S/2004 N1 was so designated because it is the first satellite (S) of Neptune (N) to be found from images taken in 2004.

Just the Facts
Orbit Size (semi-major axis):  105,283 km
Mean Radius:  9 km
Volume:  3,054 km3
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Last Updated: 12 Aug 2013