Aethra ( minor planet designation: 132 Aethra) is a metallic asteroid and

Mars-crosser A Mars-crossing asteroid (MCA, also Mars-crosser, MC) is an asteroid whose orbit crosses that of Mars. Some Mars-crossers numbered below 100000 are listed here. They include the two numbered Mars trojans 5261 Eureka and . Many databases, for in ...

on an eccentric orbit from the

asteroid belt The asteroid belt is a torus-shaped region in the Solar System, located roughly between the orbits of the planets Jupiter and Mars. It contains a great many solid, irregularly shaped bodies, of many sizes, but much smaller than planets, c ...

. It measures approximately 40 kilometers in diameter. It was discovered by

James Craig Watson James Craig Watson (January 28, 1838 – November 22, 1880) was a Canadian-American astronomer, discoverer of comets and minor planets, director of the University of Michigan's Detroit Observatory in Ann Arbor, and awarded with the Lalande Priz ...

in 1873 and is the first such

Mars-crosser asteroid A Mars-crossing asteroid (MCA, also Mars-crosser, MC) is an asteroid whose orbit crosses that of Mars. Some Mars-crossers numbered below 100000 are listed here. They include the two numbered Mars trojans 5261 Eureka and . Many databases, for in ...

to be identified. As a Mars-crosser asteroid, Aethra is the lowest numbered asteroid to not have

proper orbital elements __NOTOC__ The proper orbital elements or proper elements of an orbit are constants of motion of an object in space that remain practically unchanged over an astronomically long timescale. The term is usually used to describe the three quantitie ...

due to recurring perturbations by Mars. It has a rather eccentric

orbit In celestial mechanics, an orbit is the curved trajectory of an object such as the trajectory of a planet around a star, or of a natural satellite around a planet, or of an artificial satellite around an object or position in space such as ...

that sometimes brings it closer to the

Sun The Sun is the star at the center of the Solar System. It is a nearly perfect ball of hot plasma, heated to incandescence by nuclear fusion reactions in its core. The Sun radiates this energy mainly as light, ultraviolet, and infrared radi ...

than the

planet A planet is a large, rounded astronomical body that is neither a star nor its remnant. The best available theory of planet formation is the nebular hypothesis, which posits that an interstellar cloud collapses out of a nebula to create a you ...

Mars Mars is the fourth planet from the Sun and the second-smallest planet in the Solar System, only being larger than Mercury. In the English language, Mars is named for the Roman god of war. Mars is a terrestrial planet with a thin at ...

. With an original observation arc of only 22 days, 132 Aethra was a

lost asteroid A minor planet is "lost" when today's observers cannot find it, because its location is too uncertain to target observations. This happens if the orbital elements of a minor planet are not known accurately enough, typically because the observat ...

between 1873 and 1922. The varying light curve of the asteroid implies an elongated or irregular shape for its body. It is named after Aethra, the mother of

Theseus Theseus (, ; grc-gre, Θησεύς ) was the mythical king and founder-hero of Athens. The myths surrounding Theseus his journeys, exploits, and friends have provided material for fiction throughout the ages. Theseus is sometimes describ ...

Greek mythology A major branch of classical mythology, Greek mythology is the body of myths originally told by the ancient Greeks, and a genre of Ancient Greek folklore. These stories concern the origin and nature of the world, the lives and activities ...

References

External links

* * Mars-crossing asteroids Aethra Aethra M-type asteroids (Tholen) Xe-type asteroids (SMASS) 18730613 {{Beltasteroid-stub