Quaoar-weywot hst.jpg
Quaoar and Weywot (left of Quaoar) imaged by the Hubble Space Telescope in 2006
Discovered byMichael E. Brown
Discovery dateFebruary 22, 2007
Quaoar I
S/2006 (50000) 1
Orbital characteristics[1][2]
Periapsis12470±688 km
Apoapsis16530±912 km
14500±800 km
12.438±0.005 d
Satellite of50000 Quaoar
Physical characteristics
Mean diameter
~170 km (occultation)[3]
81±11 km[4]
74 km[1]

Weywot, officially (50000) Quaoar I Weywot, is the only known moon of the trans-Neptunian planetoid 50000 Quaoar. Discovered by Michael Brown and T.A. Suer using images acquired by the Hubble Space Telescope on 14 February 2006, its existence was announced in an IAU Circular notice published on 22 February 2007.[5][2] Weywot has an estimated diameter of 170 km (110 mi) (approximately 15% of its primary).[3] The satellite was found at 0.35 arcseconds from Quaoar with an apparent magnitude difference of 5.6.[6]


Two possible orbits for Weywot have been determined from the observations: the first is a prograde orbit with an orbital inclination of 14 degrees, the second a retrograde orbit with an orbital inclination of 30 degrees (150 degrees); the other parameters are very similar between the two orbits. Weywot orbits at a distance of 14,500 km (9,000 mi) from Quaoar and has an orbital eccentricity of about 0.14. It completes one orbit in about 12.5 days.[1]

Physical characteristics[]

As of 2019 Weywot is estimated to be around 170 km (110 mi) in diameter, based on a stellar occultation by Weywot in 2019.[3] Weywot was estimated to be 81 km (50 mi) in diameter, based on observations with the Herschel Space Observatory in 2013.[4] Prior to the Herschel Space Observatory measurements, Weywot was measured be about 74 km (112 of Quaoar) according to its apparent magnitude, under the assumption that Weywot has an equal albedo and density to Quaoar. Weywot is estimated to only have 12000 the mass of Quaoar.[1]


Upon discovery, Weywot was issued a provisional designation, S/2006 (50000) 1. Brown left the choice of a name up to the Tongva, whose creator-god Quaoar had been named after. The Tongva chose the sky god Weywot, son of Quaoar.[7] The naming of Weywot was officially announced in a Minor Planet Circular notice published on 4 October 2009.[8] It was thought that Weywot may have originated from a collision with Quaoar and another large Kuiper belt object.[9]


  1. ^ a b c d Fraser, Wesley C.; Brown, Michael E. (May 2010). "Quaoar: A Rock in the Kuiper Belt". The Astrophysical Journal. 714 (2): 1547–1550. arXiv:1003.5911. Bibcode:2010ApJ...714.1547F. doi:10.1088/0004-637X/714/2/1547.
  2. ^ a b Wm. Robert Johnston (21 September 2014). "(50000) Quaoar". Johnston's Archive. Retrieved 26 May 2009.
  3. ^ a b c Kretlow, M. (January 2020). "Beyond Jupiter – (50000) Quaoar" (PDF). Journal for Occultation Astronomy. 10 (1): 24–31. Bibcode:2020JOA....10a..24K.
  4. ^ a b c Fornasier, S.; Lellouch, E.; Müller, T.; Santos-Sanz, P.; Panuzzo, P.; Kiss, C.; et al. (July 2013). "TNOs are Cool: A survey of the trans-Neptunian region. VIII. Combined Herschel PACS and SPIRE observations of nine bright targets at 70-500 µm". Astronomy and Astrophysics. 555: 22. arXiv:1305.0449v2. Bibcode:2013A&A...555A..15F. doi:10.1051/0004-6361/201321329.
  5. ^ Green, Daniel W. E. (22 February 2007). "Satellites of 2003 AZ_84, (50000), (55637), and (90482)". IAU Circular. Central Bureau for Astronomical Telegrams (8812): 1. Bibcode:2007IAUC.8812....1B. Archived from the original on 19 July 2011.
  6. ^ Distant EKO The Kuiper Belt Electronic newsletter, March 2007
  7. ^ "Heavenly Bodies and the People of the Earth", Nick Street, Search Magazine, July/August 2008
  8. ^ Minor Planet Circular 67220 naming of Weywot
  9. ^ Howell, Elizabeth (9 May 2014). "Quaoar: Planetoid Beyond Pluto". space.com. Retrieved 14 March 2019.