In astronomy, a double planet is a binary satellite system where both objects are planets, or planetary-mass objects, that share an orbital axis external to both planetary bodies.
Brian Geoffrey Marsden was a British astronomer and the longtime director of the Minor Planet Center (MPC) at the Center for Astrophysics | Harvard & Smithsonian.
69230 Hermes is a sub-kilometer sized asteroid and binary system on an eccentric orbit, classified as a potentially hazardous asteroid and near-Earth object of the Apollo group, that passed Earth at approximately twice the distance of the Moon on 30 October 1937. The asteroid was named after Hermes from Greek mythology. It is noted for having been the last remaining named lost asteroid, rediscovered in 2003. The S-type asteroid has a rotation period of 13.9 hours. Its synchronous companion was discovered in 2003. The primary and secondary are similar in size; they measure approximately 810 meters (2,700 ft) and 540 meters (1,800 ft) in diameter, respectively.
Schelte John "Bobby" Bus is an American astronomer and discoverer of minor planets at the Institute for Astronomy of the University of Hawaii and deputy director of NASA's Infrared Telescope Facility (IRTF) at the Mauna Kea Observatory in Hawaii, United States.
David Clifford Jewitt is a British-American astronomer who studies the Solar System, especially its minor bodies. He is based at the University of California, Los Angeles, where he is a Member of the Institute for Geophysics and Planetary Physics, the Director of the Institute for Planets and Exoplanets, Professor of Astronomy in the Department of Physics and Astronomy and Professor of Astronomy in the Department of Earth, Planetary and Space Sciences. He is best known for being the first person to discover a body beyond Pluto and Charon in the Kuiper belt.
Takeshi Urata was a Japanese astronomer. He was a prolific discoverer of asteroids, observing at Nihondaira Observatory.
Marc William Buie is an American astronomer and prolific discoverer of minor planets who works at the Southwest Research Institute in Boulder, Colorado in the Space Science Department. Formerly he worked at the Lowell Observatory in Flagstaff, Arizona, and was the Sentinel Space Telescope Mission Scientist for the B612 Foundation, which is dedicated to protecting Earth from asteroid impact events.
The definition of planet has changed several times since the word was coined by the ancient Greeks. Greek astronomers employed the term ἀστέρες πλανῆται, 'wandering stars', for star-like objects which apparently moved over the sky. Over the millennia, the term has included a variety of different celestial bodies, from the Sun and the Moon to satellites and asteroids.
1604 Tombaugh, provisional designation 1931 FH, is a rare-type Eos asteroid from the outer region of the asteroid belt, approximately 32 kilometers in diameter. It was discovered on 24 March 1931, by American astronomer Carl Otto Lampland at Lowell Observatory in Flagstaff, Arizona, in the United States. It was named after the discoverer of Pluto, Clyde Tombaugh.
659 Nestor is a dark Jupiter trojan from the Greek camp, approximately 110 kilometers in diameter. It was discovered on 23 March 1908, by German astronomer Max Wolf at Heidelberg Observatory in southern Germany, and named after King Nestor from Greek mythology. The carbonaceous Jovian asteroid belongs to the 20 largest Jupiter trojans and has a rotation period of 15.98 hours.
A dwarf planet is a small planetary-mass object that is in direct orbit of the Sun, smaller than any of the eight classical planets. The prototypical dwarf planet is Pluto. The interest of dwarf planets to planetary geologists is that they may be geologically active bodies, an expectation that was borne out in 2015 by the Dawn mission to Ceres and the New Horizons mission to Pluto.
The International Astronomical Union (IAU) defined in August 2006 that, in the Solar System, a planet is a celestial body that:
- is in orbit around the Sun,
- has sufficient mass to assume hydrostatic equilibrium, and
- has "cleared the neighbourhood" around its orbit.
1404 Ajax is a carbonaceous Jupiter trojan from the Greek camp, approximately 83 kilometers kilometers in diameter. It was discovered on 17 August 1936, by German astronomer Karl Reinmuth at Heidelberg Observatory in southern Germany, and named after the legendary warrior Ajax from Greek mythology. The assumed C-type asteroid belongs to the 40 largest Jupiter trojans and has a longer than average rotation period of 29.4 hours.
Julio Ángel Fernández Alves is a Uruguayan astronomer and teacher, member of the department of astronomy at the Universidad de la República in Montevideo. He is also a member of PEDECIBA,, and the Uruguayan Society of Astronomy. From 2005 to 2010, he was the Dean of the Universidad de la Republica's Faculty of Sciences. The asteroid 5996 Julioangel, discovered in 1983, was named after him.
2873 Binzel, provisional designation 1982 FR, is a stony Florian asteroid and binary system from the inner regions of the asteroid belt, approximately 6.5 kilometers in diameter. It was discovered on 28 March 1982, by American astronomer Edward Bowell at the Anderson Mesa Station in Flagstaff, Arizona. The asteroid was named after astronomer Richard Binzel. Its 1.6-kilometer minor-planet moon was discovered in 2019.
1585 Union, provisional designation 1947 RG, is a dark background asteroid from the outer regions of the asteroid belt, approximately 52 kilometers in diameter. It was discovered on 7 September 1947, by South African astronomer Ernest Johnson at the Union Observatory in Johannesburg, South Africa. The asteroid was named after the discovering observatory.
1941 Wild, provisional designation 1931 TN1, is an eccentric Hildian asteroid from the outermost region of the asteroid belt, approximately 20 kilometers in diameter.
1257 Móra, provisional designation 1932 PE, is an asteroid from the inner regions of the asteroid belt, approximately 15 kilometers in diameter. It was discovered on 8 August 1932, by German astronomer Karl Reinmuth at Heidelberg Observatory in southwest Germany. The asteroid was named after Hungarian astronomer Károly Móra.
Gonzalo Tancredi is an Uruguayan astronomer and full professor in the Department of Astronomy at the University of the Republic in Montevideo, Uruguay. He is an active member of the International Astronomical Union (IAU) and investigator at Los Molinos Observatory.
