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Vulcan was a theorized planet that some pre-20th century astronomers thought existed in an orbit between Mercury and the Sun. Speculation about, and even purported observations of, intermercurial bodies or planets date back to the beginning of the 17th century. The case for their probable existence was bolstered by the French mathematician who had used disturbances in the orbit of Uranus to predict the existence of planet Neptune, Urbain Le Verrier. By 1859 he had confirmed unexplained peculiarities in Mercury's orbit and predicted they had to be the result of gravitational influences of another unknown nearby planet or series of asteroids. A French amateur astronomer's report that he had observed an object passing in front of the Sun that same year led Le Verrier to announce that the long sought after planet, which he gave the name Vulcan, had been discovered at last.
The Aten asteroids are a dynamical group of asteroids whose orbits bring them into proximity with Earth. By definition, Atens are Earth-crossing asteroids (a < 1.0 AU and Q > 0.983 AU). The group is named after 2062 Aten, the first of its kind, discovered on 7 January 1976 by American astronomer Eleanor Helin at Palomar Observatory. As of November 2023, 2,646 Atens have been discovered, of which 256 are numbered, 14 are named, and 102 are classified as potentially hazardous asteroids.
Atira asteroids or Apohele asteroids, also known as interior-Earth objects (IEOs), are asteroids whose orbits are entirely confined within Earth's orbit; that is, their orbit has an aphelion smaller than Earth's perihelion, which is 0.983 astronomical units (AU). Atira asteroids are by far the least numerous group of near-Earth objects, compared to the more populous Aten, Apollo and Amor asteroids.
(99907) 1989 VA is a very eccentric, stony asteroid and near-Earth object, approximately 1 kilometer in diameter. It was discovered on 2 November 1989, by American astronomer couple Carolyn and Eugene Shoemaker and Canadian astronomer David Levy at the Palomar Observatory on Mount Palomar, California.
(33342) 1998 WT24 is a bright, sub-kilometer asteroid, classified as near-Earth object and potentially hazardous asteroid (PHA) of the Aten group, located in Venus's zone of influence that has frequent close encounters with Mercury, Venus, and Earth. It made a close approach to Earth on 11 December 2015, passing at a distance of about 4.2 million kilometers (2.6 million miles, 11 lunar distances) and reaching about apparent magnitude 11.
163693 Atira, provisional designation 2003 CP20, is a stony asteroid, dwelling in the interior of Earth's orbit. It is classified as a near-Earth object. Atira is a binary asteroid, a system of two asteroids orbiting their common barycenter. The primary component with a diameter of approximately 4.8 kilometers (3 miles) is orbited by a minor-planet moon that measures about 1 km (0.6 mi). Atira was discovered on 11 February 2003, by astronomers with the Lincoln Near-Earth Asteroid Research at Lincoln Laboratory's Experimental Test Site near Socorro, New Mexico, in the United States.
(101869) 1999 MM, provisional designation 1999 MM is a sub-kilometer asteroid on an eccentric orbit, classified as a near-Earth object and potentially hazardous asteroid of the Apollo group. It was discovered on 20 June 1999, by the Lowell Observatory Near-Earth-Object Search (LONEOS) at its U.S. Anderson Mesa Station in Flagstaff, Arizona. The first observation was made by Catalina Sky Survey just 8 days before its official discovery.
(459883) 2014 JX55 is an asteroid from the central regions of the asteroid belt. After its first observations as 2007 EB26 in 2007, it was considered an inner heliospheric asteroid and near-Earth object with one of the closest perihelions ever observed of any body orbiting the Sun, until further observations invalidated the conclusions from early observations. The object measures approximately 2.8 kilometers (1.7 miles) in diameter.
(31345) 1998 PG is an eccentric, stony asteroid and binary system, classified as near-Earth object of the Amor group of asteroids, approximately 900 meters in diameter. It minor-planet moon, S/2001 (31345) 1, has an estimated diameter of 270 meters.
(374158) 2004 UL is a sub-kilometer asteroid on an outstandingly eccentric orbit, classified as near-Earth object and potentially hazardous asteroid of the Apollo group. The object is known for having the second-smallest perihelion of any known asteroid, after (137924) 2000 BD19.
(386454) 2008 XM is a highly eccentric, sub-kilometer-sized asteroid, with one of the smallest known perihelions among all minor planets. It is classified as near-Earth object of the Apollo group and was discovered on 2 December 2008, by the LINEAR program at Lincoln Laboratory's Experimental Test Site in Socorro, New Mexico, United States.
(456938) 2007 YV56, provisional designation 2007 YV56, is a sub-kilometer asteroid on an eccentric orbit, classified as a near-Earth object and potentially hazardous asteroid of the Apollo group, approximately 190–360 meters (620–1,200 ft) in diameter. It was discovered on 31 December 2007, by astronomers of the Catalina Sky Survey conducted at the Catalina Station in Arizona, United States.
2018 GE3 is a sub-kilometer asteroid on a highly eccentric orbit, classified as a near-Earth object of the Apollo group, approximately 48–110 meters (160–360 feet) in diameter. It was first observed on 14 April 2018, by astronomers with the Catalina Sky Survey one day prior to its sub-lunar close encounter with Earth at 0.5 lunar distance. It is one of the largest known asteroids (possibly the largest) in observational history to ever pass that close to Earth (also see list).
(85182) 1991 AQ, provisional designation 1991 AQ, is a stony asteroid on a highly eccentric orbit, classified as near-Earth object and potentially hazardous asteroid of the Apollo group, approximately 1.1 kilometers in diameter. It was discovered on 14 January 1991, by American astronomer Eleanor Helin at the Palomar Observatory in California. Based on its brightness variation of 0.69 magnitude, this Q-type asteroid is likely elongated. It belongs to the small group of potentially hazardous asteroids larger than one kilometer.
2019 AQ3 is an inclined near-Earth object of the small Atira group from the innermost region of the Solar System, estimated to measure 1.4 kilometers (0.9 miles) in diameter. Among the hundreds of thousands known asteroids, 2019 AQ3's orbit was thought to have likely the smallest semi-major axis (0.589 AU) and aphelion (0.77 AU), that is, the orbit's average distance and farthest point from the Sun, respectively. The object was first observed on 4 January 2019, by astronomers at Palomar's Zwicky Transient Facility in California, with recovered images dating back to 2015.
2019 LF6 is a near-Earth object of the Atira group. After 2021 PH27, it has the second-smallest semi-major axis among the known asteroids (0.555 AU), beating the previously-held record of 2019 AQ3. It orbits the Sun in 151 days.
594913 ꞌAylóꞌchaxnim (provisional designation 2020 AV2) is a large near-Earth asteroid discovered by the Zwicky Transient Facility on 4 January 2020. It is the first asteroid discovered to have an orbit completely within Venus's orbit, and is thus the first and only known member of the eponymous ꞌAylóꞌchaxnim (informally named Vatira before its discovery) population of Atira-class asteroids. ꞌAylóꞌchaxnim has the smallest known aphelion and third-smallest known semi-major axis among all asteroids. With an absolute magnitude approximately 16.2, the asteroid is expected to be larger than 1 km in diameter.
(231937) 2001 FO32 is a near-Earth asteroid classified as a potentially hazardous asteroid of the Apollo group. With an estimated diameter around 550 m (1,800 ft), it was discovered by the Lincoln Near-Earth Asteroid Research at Socorro, New Mexico on 23 March 2001. The asteroid safely passed by Earth on 21 March 2021 16:03 UTC from a closest approach distance of 0.0135 AU (2.02 million km; 1.25 million mi), or 5.25 lunar distances (LD). During the day before closest approach, 2001 FO32 reached a peak apparent magnitude of 11.7 and was visible to ground-based observers with telescope apertures of at least 20 cm (8 in). It is the largest and one of the fastest asteroids to approach Earth within 10 LD (3.8 million km; 2.4 million mi) in 2021.
2021 PH27 is a near-Earth asteroid of the Atira group. It was discovered by Scott Sheppard using the Dark Energy Survey's DECam imager at NOIRLab's Cerro Tololo Inter-American Observatory on 13 August 2021. 2021 PH27 has the smallest semi-major axis and shortest orbital period among all known asteroids as of 2021, with a velocity at perihelion of 106 km/s (240,000 mph). It also has the largest value of the relativistic perihelion shift, 1.6 times that of Mercury. With an absolute magnitude of 17.7, the asteroid is estimated to be larger than 1 kilometer (0.6 miles) in diameter.
2022 AP7 is a kilometer-sized Apollo asteroid and potentially hazardous object orbiting between Venus and Jupiter. It was discovered on 13 January 2022 by Scott Sheppard at Cerro Tololo Observatory. Based on its absolute magnitude (H), 2022 AP7 is likely the largest potentially hazardous object identified in the eight years prior to its 2022 discovery.
References
- 1 2 3 4 5 6 7 "JPL Small-Body Database Browser: 434326 (2004 JG6)" (2015-05-29 last obs.). Jet Propulsion Laboratory . Retrieved 2 June 2017.
- 1 2 3 4 5 "434326 (2004 JG6)". Minor Planet Center. Retrieved 25 April 2017.
- 1 2 3 "434326 (2004 JG6)". NEODyS-2, Near Earth Objects – Dynamic Site. Retrieved 25 April 2017.
- 1 2 3 "LONEOS Discovers Asteroid with the Smallest Orbit". Space Daily. 12 July 2004. Retrieved 25 April 2017.
