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Quaoar-weywot hst.jpg
Quaoar and Weywot (left of Quaoar) imaged by the Hubble Space Telescope in 2006
Discovered by Michael E. Brown
Discovery dateFebruary 22, 2007
Quaoar I
Pronunciation /ˈwwɒt/
S/2006 (50000) 1
Orbital characteristics [1] [2]
Periapsis 12470±688 km
Apoapsis 16530±912 km
14500±800 km
Eccentricity 0.148±0.025
12.438±0.005 d
Inclination 14°±
Satellite of 50000 Quaoar
Physical characteristics
Mean diameter
~170 km (occultation) [3]
81±11 km [4]
74 km [1]
24.9±0.2 [4]

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]

Related Research Articles

Kuiper belt Area of the Solar System beyond the planets, comprising small bodies

The Kuiper belt is a circumstellar disc in the outer Solar System, extending from the orbit of Neptune at 30 astronomical units (AU) to approximately 50 AU from the Sun. It is similar to the asteroid belt, but is far larger—20 times as wide and 20–200 times as massive. Like the asteroid belt, it consists mainly of small bodies or remnants from when the Solar System formed. While many asteroids are composed primarily of rock and metal, most Kuiper belt objects are composed largely of frozen volatiles, such as methane, ammonia, and water. The Kuiper belt is home to three objects identified as dwarf planets by the IAU: Pluto, Haumea, and Makemake. Some of the Solar System's moons, such as Neptune's Triton and Saturn's Phoebe, may have originated in the region.

Trans-Neptunian object Any object in the Solar System that orbits the Sun at a greater average distance than Neptune

A trans-Neptunian object (TNO), also written transneptunian object, is any minor planet or dwarf planet in the Solar System that orbits the Sun at a greater average distance than Neptune, which has a semi-major axis of 30.1 astronomical units (AU).

28978 Ixion Plutino

28978 Ixion, provisional designation 2001 KX76, is a large trans-Neptunian object and a possible dwarf planet. It is located in the Kuiper belt, a region of icy objects orbiting beyond Neptune in the outer Solar System. Ixion is classified as a plutino, a dynamical class of objects in a 2:3 orbital resonance with Neptune. It was discovered in May 2001 by astronomers of the Deep Ecliptic Survey at the Cerro Tololo Inter-American Observatory, and was announced in July 2001. The object is named after the Greek mythological figure Ixion, who was a king of the Lapiths.

20000 Varuna Kuiper belt object

20000 Varuna, provisional designation 2000 WR106, is a large trans-Neptunian object in the Kuiper belt. It was discovered in December 2000 by American astronomer Robert McMillan during a Spacewatch survey at the Kitt Peak National Observatory. It has an elongated shape due to its rapid rotation. It is named after the Hindu deity Varuna, one of the oldest deities mentioned in the Vedic texts.

90482 Orcus Trans-Neptunian object and dwarf planet

Orcus is a trans-Neptunian dwarf planet with a large moon, Vanth. It has a diameter of 910 km (570 mi). The surface of Orcus is relatively bright with albedo reaching 23 percent, neutral in color and rich in water ice. The ice is predominantly in crystalline form, which may be related to past cryovolcanic activity. Other compounds like methane or ammonia may also be present on its surface. Orcus was discovered by American astronomers Michael Brown, Chad Trujillo, and David Rabinowitz on 17 February 2004.

38628 Huya Trans-Neptunian object

38628 Huya ( hoo-YAH), provisional designation 2000 EB173, is a binary trans-Neptunian object located in the Kuiper belt, a region of icy objects orbiting beyond Neptune in the outer Solar System. Huya is classified as a plutino, a dynamical class of trans-Neptunian objects with orbits in a 3:2 orbital resonance with Neptune. It was discovered by the Quasar Equatorial Survey Team and was identified by Venezuelan astronomer Ignacio Ferrín in March 2000. It is named after Juyá, the mythological rain god of the Wayuu people native to South America.

<span class="nowrap">(55565) 2002 AW<sub>197</sub></span> Classical Kuiper belt object

(55565) 2002 AW197 is a classical, non-resonant trans-Neptunian object from the Kuiper belt in the outermost region of the Solar System, also known as cubewano. With a likely diameter of at least 700 kilometers (430 miles), it is approximately tied with 2002 MS4 and 2013 FY27 (to within measurement uncertainties) as the largest unnamed object in the Solar System. It was discovered at Palomar Observatory in 2002.

<span class="nowrap">(55637) 2002 UX<sub>25</sub></span> Spitzer dwarf-planet candidate

(55637) 2002 UX25 is a trans-Neptunian object that orbits the Sun in the Kuiper belt beyond Neptune. This TNO briefly garnered scientific attention when it was found to have an unexpectedly low density of about 0.82 g/cm3.

<span class="nowrap">(84522) 2002 TC<sub>302</sub></span> Large trans-Neptunian object

(84522) 2002 TC302, prov. designation: 2002 TC302, is a mid-sized trans-Neptunian object located in the outermost region of the Solar System. It was discovered on 9 October 2002, by American astronomers Mike Brown, Chad Trujillo and David Rabinowitz at the Palomar Observatory in California. The resonant trans-Neptunian object stays in a 2:5 resonance with Neptune. It has a reddish color, a rotation period of 56.1 hours and measures at least 500 kilometers (310 miles) in diameter.

<span class="nowrap">(55636) 2002 TX<sub>300</sub></span>

(55636) 2002 TX300 is a bright Kuiper belt object in the outer Solar System estimated to be about 286 kilometres (178 mi) in diameter. It is a large member of the Haumea family that was discovered on 15 October 2002 by the Near-Earth Asteroid Tracking (NEAT) program.

<span class="nowrap">(307261) 2002 MS<sub>4</sub></span> Classical Kuiper belt object

(307261) 2002 MS4 is a large classical Kuiper belt object and a possible dwarf planet in the Kuiper belt, a region of icy planetesimals beyond Neptune. It was discovered in 2002 by Chad Trujillo and Michael Brown, and has precovery images back to 8 April 1954.

<span class="nowrap">(208996) 2003 AZ<sub>84</sub></span> Plutino

(208996) 2003 AZ84 is a trans-Neptunian object with a possible moon from the outer regions of the Solar System. It is approximately 940 kilometers across its longest axis, as it has an elongated shape. It belongs to the plutinos – a group of minor planets named after its largest member Pluto – as it orbits in a 2:3 resonance with Neptune in the Kuiper belt. It is the third-largest known plutino, after Pluto and Orcus. It was discovered on 13 January 2003, by American astronomers Chad Trujillo and Michael Brown during the NEAT survey using the Samuel Oschin telescope at Palomar Observatory.

79360 Sila–Nunam

79360 Sila–Nunam, provisional designation 1997 CS29, is a double cold classical Kuiper belt object (cubewano) with components of almost equal size, orbiting beyond Neptune in the Solar System. The name of the system is the combined names of the two bodies, Sila and Nunam.

<span class="nowrap">(84922) 2003 VS<sub>2</sub></span> Trans-Neptunian object

(84922) 2003 VS2 is a trans-Neptunian object discovered by the Near Earth Asteroid Tracking program on 14 November 2003. Like Pluto, it is in a 2:3 orbital resonance with Neptune and is thus a plutino. Analysis of light-curve suggests that it is not a dwarf planet.

225088 Gonggong Dwarf planet in the scattered-disc

Gonggong (225088 Gonggong or provisional designation: 2007 OR10) is a dwarf planet, a member of the scattered disc beyond Neptune. It has a highly eccentric and inclined orbit during which it ranges from 34–101 astronomical units (5.1–15.1 billion kilometers; 3.2–9.4 billion miles) from the Sun. As of 2019, its distance from the Sun is 88 AU (13.2×10^9 km; 8.2×10^9 mi), and it is the sixth-farthest known Solar System object. Gonggong is in a 3:10 orbital resonance with Neptune, in which it completes three orbits around the Sun for every ten orbits completed by Neptune. Gonggong was discovered in July 2007 by American astronomers Megan Schwamb, Michael Brown, and David Rabinowitz at the Palomar Observatory, and the discovery was announced in January 2009.

50000 Quaoar Cold classical Kuiper belt object

Quaoar (50000 Quaoar), provisional designation 2002 LM60, is a dwarf planet in the Kuiper belt, a region of icy planetesimals beyond Neptune. A non-resonant object (cubewano), it measures approximately 1,121 km (697 mi) in diameter, about half the diameter of Pluto. The object was discovered by American astronomers Chad Trujillo and Michael Brown at the Palomar Observatory on 4 June 2002. Signs of water ice on the surface of Quaoar have been found, which suggests that cryovolcanism may be occurring on Quaoar. A small amount of methane is present on its surface, which can only be retained by the largest Kuiper belt objects. In February 2007, Weywot, a synchronous moon in orbit around Quaoar, was discovered by Brown. Weywot is measured to be 170 km (110 mi) across. Both objects were named after mythological figures from the Native American Tongva people in Southern California. Quaoar is the Tongva creator deity and Weywot is his son.

Vanth (moon) Moon of 90482 Orcus

Vanth, full designation (90482) Orcus I Vanth, is the single known natural satellite of the plutino and likely dwarf planet 90482 Orcus. With a diameter of about 440 km, it is half the size of Orcus and probably the third-largest known moon of a known trans-Neptunian object, after Pluto I Charon and Eris I Dysnomia, though it is possible that the poorly resolved Varda I Ilmarë or Haumea I Hiʻiaka might be comparable in size. Vanth was discovered by Michael Brown and T.-A. Suer using discovery images taken by the Hubble Space Telescope on 13 November 2005. The discovery was announced in an IAU Circular notice published on 22 February 2007.

471143 Dziewanna Scattered disc object

471143 Dziewanna, exact:, provisional designation 2010 EK139, is a trans-Neptunian object in the scattered disc, orbiting the Sun in the outermost region of the Solar System.

Actaea (moon) Moon of 120347 Salacia

Actaea, officially (120347)Salacia I Actaea, is a natural satellite of the classical Kuiper belt planetoid 120347 Salacia. Its diameter is estimated 300 km (190 mi), which is approximately one-third the diameter of Salacia; thus, Salacia and Actaea are viewed by some astronomers to be a binary system. Assuming that the following size estimates are correct, Actaea is about the sixth-biggest known moon of a trans-Neptunian object, after Charon (1212 km), Dysnomia (700 km), Vanth (443 km), Ilmarë (326 km) and Hiʻiaka (320 km), but possibly also Hiisi.

<span class="nowrap">(275809) 2001 QY<sub>297</sub></span>

(275809) 2001 QY297 is a trans-Neptunian object from the classical Kuiper belt, located in the outermost region of the Solar System. The binary classical Kuiper belt object belongs to the cold population.


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  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
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