65489 Ceto
65489 Ceto is a binary trans-Neptunian object located in the outer reaches of our solar system. Discovered on March 22, 2003, it became recognized as a binary system after its moon, Phorcys, was identified on April 11, 2006. Ceto has an estimated diameter of 174 kilometers (108.1 miles), while its companion, Phorcys, measures about 132 kilometers (82 miles). As a binary centaur, Ceto's orbit is unique as it crosses the paths of the outer planets, including Uranus and Neptune. Centaurs, like Ceto, are characterized by unstable orbits that may last only a few million years before they either escape or collide. The names Ceto and Phorcys are derived from ancient Greek mythology, reflecting their association with sea deities known for their connection to various mythical sea creatures. This classification places Ceto among only a few known binary centaurs, contributing to our understanding of the diverse bodies that populate the solar system.
65489 Ceto
FIELDS OF STUDY: Astrometry; Astrophysics; Cosmology
ABSTRACT: (65489) Ceto is a small trans-Neptunian object. Its similarly sized moon, Phorcys, qualifies Ceto as a binary system. Because of Ceto’s location and orbit, it is designated a centaur. Ceto is the second binary centaur ever discovered.
Binary Systems
In astronomy, most objects orbit another object. A binary system is a system in which two objects are close enough together that they orbit one another. More precisely, they orbit a common center of mass that lies between them.
(65489) Ceto is a binary trans-Neptunian object. Its companion in the binary system is its moon, Phorcys. Ceto was discovered on March 22, 2003, but it was not identified as binary until Phorcys was discovered on April 11, 2006. Although Ceto is larger than Phorcys, the two are fairly close in size. Ceto has an estimated diameter of 174 kilometers (108.1 miles). Phorcys is thought to be about 132 kilometers (82 miles) across.
Ceto classified as a trans-Neptunian object (TNO) because its average distance from the sun is greater than that of Neptune. However, at times its orbit brings it closer to the sun than Neptune, crossing the paths of both Uranus and Neptune. Because of this, it is also classified as a binary centaur. Ceto is only the second binary centaur to be discovered. The first one was (42355) Typhon, whose binary companion is its moon, Echidna. Typhon itself was discovered on February 5, 2002. Echidna was discovered on January 20, 2006.
Centaurs
A centaur is a small solar system body (SSSB) whose orbit crosses that of one or more of the outer planets. (A TNO is a type of SSSB.) Centaurs have very unstable orbits. An unstable orbit is one that will eventually decay. A centaur’s orbit lasts only a few million years. After that, the centaur will either escape its orbit or be destroyed in an impact.
Most centaurs exhibit attributes of both asteroids and comets. For this reason, they were named after the mythical centaur, which was said to have the torso and upper body of a human and the lower body of a horse. NASA’s Wide-Field Infrared Survey Explorer mission found that two-thirds of centaurs reflect less light, like comets, though some are brighter like asteroids.
Ceto and Phorcys
Like many space objects, Ceto and Phorcys were named after ancient Greek gods. Ceto was the goddess of the dangers of the sea, specifically sharks, whales, and sea monsters. Phorcys was her brother and husband, another powerful and dangerous sea god. Ceto and Phorcys were said to be the parents of many mythical Greek monsters, including Scylla and the Gorgons.
PRINCIPAL TERMS
- binary centaur: two small solar system bodies that orbit around a common center of mass while also following a larger, nonresonant, unstable orbit around the sun that crosses the path of one or more outer planets.
- binary trans-Neptunian object: two minor planets that orbit around a common center of mass while also following a larger orbit around the sun at a greater average distance than Neptune.
Bibliography
Barber, Elizabeth. "What Is a Space ‘Centaur’? Scientists Now Know the Answer." Christian Science Monitor. Christian Science Monitor, 26 July 2013. Web. 20 Mar. 2015.
Grundy, W. M., et al. "The Orbit, Mass, Size, Albedo, and Density of (65489) Ceto/Phorcys: A Tidally-Evolved Binary Centaur." Icarus 191.1 (2007): 286–97. Print.
"Keto." Theoi Project: Greek Mythology. Aaron J. Atsma, n.d. Web. 20 Mar. 2015.
Lacey, Sheridan, and Sarah Maddison. "Binary Asteroids." SAO Astro News. Swinburne Astronomy Online, 13 Apr. 2014. Web. 20 Mar. 2015.
Li, Jing, et al. "Hubble Space Telescope Search in Activity in High-Periihelion Objects." The Astronomical Journal, 14 Apr. 2020, iopscience.iop.org/article/10.3847/1538-3881/ab7faf. Accessed 13 June 2022.
"NASA’s WISE Finds Mysterious Centaurs May Be Comets." Jet Propulsion Laboratory. Caltech, 25 July 2013. Web. 25 Mar. 2015.
Noll, Keith S., et al. "Binaries in the Kuiper Belt." The Solar System beyond Neptune. Ed. M. A. Barucci et al. Tucson: U of Arizona P, 2008. 345–63. Print.
"Phorkys." Theoi Project: Greek Mythology. Aaron J. Atsma, n.d. Web. 20 Mar. 2015.