1143 Odysseus /oʊˈdɪsiːəs/, provisional designation 1930 BH, is a large Jupiter trojan located in the Greek camp of Jupiter's orbit. It was discovered on 28 January 1930, by German astronomer Karl Reinmuth at the Heidelberg Observatory in southwest Germany,^[1] and later named after Odysseus, the legendary hero from Greek mythology.^[3] The dark D-type asteroid has a rotation period of 10.1 hours.^[5] With a diameter of approximately 125 kilometers (78 miles), it is among the 10 largest Jovian trojans.

Odysseus is a dark Jovian asteroid orbiting in the leading Greek camp at Jupiter's L₄ Lagrangian point, 60° ahead of the Gas Giant's orbit in a 1:1 resonance (see Trojans in astronomy).^[6] It is a non-family asteroid in the Jovian background population.^[7]

It orbits the Sun at a distance of 4.8–5.7 AU once every 12 years (4,393 days; semi-major axis of 5.25 AU). Its orbit has an eccentricity of 0.09 and an inclination of 3° with respect to the ecliptic.^[4] As a Jupiter Trojan it is in a very stable orbit. Its closest approach to any major planet will be on 5 May 2083 when it will still be 3.104 AU (464,000,000 km; 289,000,000 mi) from Mars.^[b] The body's observation arc begins at Heidelberg in February 1930, three weeks after its official discovery observation.^[1]

This minor planet was named after the ancient Greek hero Odysseus (Odysseus Laertiades) in Homer's epic poem Odyssey. The official naming citation was mentioned in The Names of the Minor Planets by Paul Herget in 1955 (H 107).^[3] Another Jupiter trojan, 5254 Ulysses, is named after the Latin variant of Odysseus.

Odysseus is a dark D-type asteroid in both the Tholen classification and Bus–DeMeo classification.^[8]

According to the surveys carried out by the Infrared Astronomical Satellite IRAS, the Japanese Akari satellite and the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer (WISE), Odysseus measures between 114.62 and 130.81 kilometers in diameter and its surface has an albedo between 0.050 and 0.0753.^[10][11][12]

The Collaborative Asteroid Lightcurve Link adopts the results obtained by IRAS, that is, an albedo of 0.0753 and a diameter of 125.64 kilometers based on an absolute magnitude of 7.93.^[5] In May 2005, an asteroid occultation gave a best-fit dimension of 126 km × 126 km for the major and minor axis of the occultation ellipse.^[8][9]

An estimated mean diameter of 130, 125 or 114 kilometers, measured by Akari, IRAS and WISE, makes Odysseus the 7th, 8th or 10th largest Jupiter Trojan, respectively.^[c]

A large number of rotational lightcurves of Odysseus have been obtained since its first photometric observation by Richard Binzel in January 1988. In June 1994, the first accurate measurement of the asteroid's rotation period was made by Stefano Mottola using the former Bochum 0.61-metre Telescope at ESO's La Silla Observatory in northern Chile.^{[5][13][14][15][16][17][19][20]}

As of 2018, analysis of the best-rated lightcurve from observations by the Kepler space observatory during its K2 mission observing Campaign Field 6 in September 2015, gave a well-defined period of 10.114 hours with a brightness amplitude of 0.20 magnitude (U=3).^[5][18]

• Asteroid Lightcurve Database (LCDB), query form (info Archived 16 December 2017 at the Wayback Machine)
• Dictionary of Minor Planet Names, Google books
• Discovery Circumstances: Numbered Minor Planets (1)-(5000) – Minor Planet Center
• 1143 Odysseus at AstDyS-2, Asteroids—Dynamic Site
  • Ephemeris · Observation prediction · Orbital info · Proper elements · Observational info
• 1143 Odysseus at the JPL Small-Body Database
  • Close approach · Discovery · Ephemeris · Orbit viewer · Orbit parameters · Physical parameters