Neso also known as Neptune XIII, is the farthest non-spherical moon of Neptune. It was found by Matthew J. Holman, Brett J. Gladman, et al. on August 14, 2002, though it went unnoticed until 2003.

Neso orbits Neptune at a distance of more than 48 million km, making it the farthest known moon of any planet.

It follows a very inclined and very eccentric orbit illustrated on the diagram in relation to other irregular satellites of Neptune.

Neso is about 60 km in diameter, and assuming the mean density of 1.5 g/cm³. Its mass is estimated at 1.6×10¹⁷ kg.

Given the similarity of the orbit's parameters with Psamathe (S/2003 N 1), it was suggested that both non-spherical moons could have been a bigger moon that broke up.

Neso is named after one of the Nereids. Before the announcement of its name on February 3, 2007 (IAUC 8802), Neso was known by its designation S/2002 N 4.

• Matthew Holman's Neptune's page
• David Jewitt's pages
• Scott Sheppard's pages
• Neso in Fiction