NOTABLE ASTEROIDS & KBOS A  B  C  D  E  F  G  H  I  J  K  L  M  N  O  P  Q  R  S  T  U  V  W  X  Y  Z                    HOME ABOUT CATEGORIES SITE MAP COPYRIGHT ADVERTISE CONTACT entire Web this site 2003 EL61 (Kuiper Belt object) Discovery photo of 2003 EL61 A large and unusual Kuiper Belt object (KBO) of the type known as cubewanos. 2003 EL61 has two moons, spins very fast, and appears to be cigar-shaped. It is estimated to be about as wide as Pluto along its longest dimension and about half that along its shortest. (See largest known Kuiper Belt objects.) 2003 EL61 was discovered by a team from the California Institite of Technology consisting of Michael E. Brown, Chad Trujillo, and David Rabinowitz who had been observing the object for half a year with the 1.3-meter SMARTS Telescope. The discovery was made on Dec. 28, 2004 and announced in 2005. In September 2008, 2003 EL61 was named by the International Astronomical Union Haumea, after the goddess of childbirth and fertility in Hawaiian mythology. Fast spin Periodic variations in the brightest of 2003 EL61 are thought to be due to its exceptionally elongated shape Artist's impression of 2003 EL61 and its two moons. (Separation distances not to scale) In September 2005, researchers announced that 2003 EL61 was the fastest spinning large object known in the Solar System, rotating once every 3.9 hours. This means that instead of being roughly spherical, the object is stretched out into the shape of a squashed rugby ball. Knowing its shape, astronomers have deduced a density for 2003 EL61 more than 2.5 times that of water and a reflectivity similar to that of fresh snow. A spiralling-in effect of the object and its moons might have been be the cause of the high rotation rate. Alternatively the fast spin might be the result of a major impact in which the moons were created. The moons of 2003 EL61 Two satellites have been found in orbit around 2003 EL61. Both were discovered in 2005 and are of substantial size. S/2005 (2003 EL61) 1 was the first of 2003 EL61's moons to be found. It has been nicknamed "Rudolph" by the Caltech team which discovered it. It orbits 2003 EL61 once every 49 days at a distance of about 49,500 km, with an eccentricity of 0.050 and an inclination of 235°. Its measured brightness suggests a diameter of about 350 km, assuming it has a similar brightness to the primary. This would make it larger than all but four of the asteroids (1 Ceres, 2 Pallas, 4 Vesta, and 10 Hygiea) in the main asteroid belt. S/2005 (2003 EL61) 2 is the smaller and inner moon of 2003 EL61 at a distance of about 39,000 km from the primary. The orbital period is 34 days and the inclination 39±6° from the larger moon. Its diameter has been estimated at about 170 km. diameter ~1960×1520×1000 km density 2.6-3.3 g/cm3 albedo 0.7±0.1 absolute magnitude 0.1 eccentricity 0.189 semi-major axis 43.34 AU perihelion 35.16 AU aphelion 51.53 AU orbital period 285.4 years inclination 28.19° Related category NOTABLE ASTEROIDS, CENTAURS, AND KUIPER BELT OBJECTS Also on this site: Encyclopedia of Alternative Energy & Sustainable Living Encyclopedia of History Transport Concepts & Designs (partner site) BACK TO TOP