It was first observed on 18 November 1998, by American astronomer Marc Buie and Robert Millis at the Kitt Peak National Observatory in Arizona, United States.

[2][3][1] In December 2000, a minor-planet moon, designated S/2000 (1998 WW31) 1 with a diameter of 123 kilometers (76 miles), was discovered in its orbit.

[1] 1998 WW31 is expected to have a low albedo due to its blue (neutral) color.

On 22 December 2000, French astronomers Christian Veillet and Alain Doressoundiram in collaboration with J. Shapiro discovered the satellite using the Canada–France–Hawaii Telescope at Mauna Kea on the Big Island of Hawaii, United States.

[6][12] The Collaborative Asteroid Lightcurve Link assumes an albedo of 0.10 and calculates a system diameter of 192 kilometres (119 mi) based on an absolute magnitude of 6.7,[8] while Mike Brown finds a diameter of 267 kilometres (166 mi) with a lower albedo of 0.04.