1998 WW31
Number
-
Provisional name
1998 WW31
Class
Cubewano
Discovery date
18.11.1998, 05:09:44 UT, Kitt Peak, AZ, USA
Discovery chart
Discovery position
22 Taurus 54' Rx
Time of announcement
28.01.1999 - 22:30 UT
Orbital period
296.7 years
Orbit
  • crosses the orbit of Pluto
Aphelion
48.521 AU
Perihelion
40.541 AU
Semimajor axis
44.531 AU
Magnitude
6.1
Diameter
115 - 356 km
Inclination
6.8
 
CFHT image
1998 WW31 has a binary companion. This is the first trans-Neptunian binary discovered since Pluto. It is the most symmetrical of the known binary systems. The two objects are very close in size. The orbit is highly eccentric and the orbital period is long, very different from the Pluto-Charon system.

The mutual eclipses are estimated to happen about 50 years from now, possibly in 2055 or in 2056 (with a few years uncertainty).

Satellite
S/2000 (1998 WW31) 1
Discovery
image was taken 22.12.2000, Canada-France-Hawaii Telescope (CFHT), Mauna Kea, Hawaii, USA,
the object was found from the image in April 2001
Time of announcement
Distance between pair
22,300 km +/- 800 km
Orbital period
574 +/- 10 d