Discovery [1] [2] | |
---|---|
Discovered by | Siding Spring Survey |
Discovery site | Siding Spring Obs. |
Discovery date | 18 September 2009 |
Designations | |
2009 SH2 | |
Earth co-orbital [3] · NEO Aten [4] | |
Orbital characteristics [4] | |
Epoch 31 May 2020 (JD 2459000.5) | |
Uncertainty parameter 4 | |
Observation arc | 14 days |
Aphelion | 1.085 AU |
Perihelion | 0.8978 AU |
0.991 AU | |
Eccentricity | 0.09423 |
0.99 yr (360.46 d) | |
193.262° | |
0° 59m 55.362s / day | |
Inclination | 6.811° |
6.674° | |
13 November 2020 22:52 UT | |
101.725° | |
Earth MOID | 0.0006 AU (90,000 km) |
Physical characteristics | |
30–60 m (assumed albedo 0.05–0.25) [5] | |
1.26 h [4] | |
18.8 (at discovery) [1] | |
24.9 [4] [2] | |
2009 SH2 is a sub-kilometer near-Earth asteroid of the Aten group, discovered by the Siding Spring Survey at Siding Spring Observatory, Australia on 18 September 2009. It is in a co-orbital configuration with Earth, a type of 1:1 orbital resonance where the asteroid appears to librate around Earth's path in a horseshoe orbit when viewed in a corotating reference frame with Earth. The co-orbital state of 2009 SH2 is only temporary as it has entered it about 30 years ago and will leave it in about 100 years into the future. [3]
2009 SH2 was discovered by the Siding Spring Survey at Siding Spring Observatory, Coonabarabran, New South Wales, Australia on 18 September 2009. It was first observed in the constellation Fornax at an apparent magnitude of 18.8. [1] The asteroid was moving at an on-sky rate around 2.5 arcseconds per minute, from a distance of 0.030 AU (4.5 million km; 2.8 million mi) from Earth. [6] Follow-up observations of the asteroid were carried out by the Rio Cuarto Observatory (I20) on the following day. The asteroid was then confirmed by the Minor Planet Center and announced as 2009 SH2 on 19 September 2009. [1]
2009 SH2 orbits the Sun at an average distance of 0.99 AU once every 360 days, or approximately 0.99 years. Its orbit has an eccentricity of 0.09 and an inclination of 7° with respect to the ecliptic plane. Over the course of its orbit, its distance from the Sun ranges from 0.90 AU at perihelion to 1.08 AU at aphelion, crossing the orbit of Earth. Since its orbit crosses that of Earth's while having a semi-major axis less than 1 AU, 2009 SH2 is classified as an Aten asteroid. Its nominal orbit has a small minimum orbit intersection distance approximately 0.0006 AU (90,000 km; 56,000 mi) from Earth's orbital path and periodically makes close approaches to Earth. [4]
In 2013, astronomers Carlos and Raúl de la Fuente Marcos identified 2009 SH2 to be in a co-orbital configuration with Earth, a type of 1:1 orbital resonance where the asteroid appears to librate around Earth's path in a horseshoe orbit when viewed in a corotating reference frame with Earth. The co-orbital state of 2009 SH2 is only temporary as it has entered it about 30 years ago and will leave it in about 100 years into the future. [3]
Based on an magnitude-to-diameter conversion and a measured absolute magnitude of 24.9, 2009 SH2 measures between 30 and 60 meters in diameter for an assumed geometric albedo of 0.25 and 0.05, respectively. [2] [5] A rotation period of 1.26 h has been tentatively measured from its lightcurve. [4]
2062 Aten, provisional designation 1976 AA, is a stony sub-kilometer asteroid and namesake of the Aten asteroids, a subgroup of near-Earth objects. The asteroid was named after Aten from Egyptian mythology.
524522 Zoozve (provisional designation 2002 VE68) is a sub-kilometer sized asteroid and temporary quasi-moon of Venus. Discovered in 2002, it was the first such object to be discovered around a major planet in the Solar System. It has nearly the same orbital period around the Sun that Venus does. In a frame of reference rotating with Venus, it appears to travel around it during one Venerean year, but it orbits the Sun, not Venus.
(480808) 1994 XL1 is a sub-kilometer asteroid, classified as near-Earth object and potentially hazardous asteroid of the Aten group, approximately 200 meters (700 feet) in diameter. It was discovered on 6 December 1994, by Scottish–Australian astronomer Robert McNaught at Siding Spring Observatory in Australia. It was one of the first asteroids discovered to have a semi-major axis less than Venus.
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.
(6491) 1991 OA is a highly eccentric, stony asteroid, classified as near-Earth object and potentially hazardous asteroid, approximately half a kilometer in diameter. It was discovered on 16 July 1991, by American astronomer Henry E. Holt at the U.S. Palomar Observatory in California.
2013 BS45 (also written 2013 BS45) is a horseshoe companion to the Earth like 3753 Cruithne. Like Cruithne, it does not orbit the Earth in the normal sense and at times it is on the other side of the Sun, yet it still periodically comes nearer to the Earth in sort of halo orbit before again drifting away. While not a traditional natural satellite, it does not quite have normal heliocentric orbit either and these are sometimes called quasi-satellties or horseshoe orbits.
2012 FC71, also written 2012 FC71, is a small asteroid trapped in a Kozai resonance with the Earth.
2000 EM26 is a sub-kilometer near-Earth object and potentially hazardous asteroid of the Aten group, approximately 110 meters (360 feet) in diameter. It was first observed by astronomers of the LINEAR program on 5 March 2000 and followed until 14 March 2000, by which time it had dimmed to apparent magnitude 20 and was 40° from the Moon. By 17 March 2000 it was only 4 degrees from a 90% waxing gibbous moon. It has never been listed on the Sentry Risk Table because none of the potential orbital solutions create a risk of impact in the next ~100 years. The asteroid safely passed Earth on 17–18 February 2014. Due to a then-poorly determined orbit, the asteroid may have been significantly further from Earth and dozens of degrees from where the telescope was pointed during the 2014 approach.
2014 OL339 (also written 2014 OL339) is an Aten asteroid that is a temporary quasi-satellite of Earth, the fourth known Earth quasi-satellite.
2015 SO2 (also written 2015 SO2) is an Aten asteroid that is a temporary horseshoe companion to the Earth, the ninth known Earth horseshoe librator. Prior to its most recent close encounter with our planet (2015 September 30) it was an Apollo asteroid.
2015 XX169 (also written 2015 XX169) is an Apollo asteroid that is a temporary horseshoe companion to the Earth, the tenth known Earth horseshoe librator. A close encounter with the Earth on 14 December 2015 caused the value of the semi-major axis of 2015 XX169 to drift slowly upwards, and the object evolved from an Aten asteroid to an Apollo asteroid about a year after this close approach.
2017 DR109, is a micro-asteroid, classified as near-Earth object of the Apollo group and Aten group, respectively. It is currently trapped in a 1:1 mean motion resonance with the Earth of the horseshoe type. The object was first observed on 27 February 2017, by astronomers of the Catalina Sky Survey conducted at Mount Lemmon Observatory, Arizona, United States.
2017 OO1 is a small asteroid, classified as near-Earth object of the Aten group, approximately 35–76 meters (115–249 feet) in diameter. It was first observed on 23 July 2017, by the robotic ATLAS survey at Mauna Loa Observatory, Hawaii, two days after the object had approached Earth at 0.33 lunar distances on 21 July 2017.
2013 GM3 is a micro-asteroid, classified as near-Earth object of the Aten group, approximately 20 meters in diameter. It was first observed on 3 April 2013, by astronomers of the Mount Lemmon Survey conducted at the Mount Lemmon Observatory near Tucson, Arizona, United States.
2018 DV1 is a micro-asteroid, classified as a near-Earth object of the Aten group, approximately 6–12 meters (20–40 feet) in diameter. It was first observed on 26 February 2018, by astronomers of the Mount Lemmon Survey at Mount Lemmon Observatory, Arizona, five days prior to its sub-lunar close encounter with Earth at less than 0.3 lunar distance.
2018 RY7, is a small near-Earth object of the Apollo group. It is currently trapped in a 3:5 mean motion resonance with Venus. The object was first observed on 14 September 2018, by astronomer B. M. Africano with the Mount Lemmon Survey at Mount Lemmon Observatory, Arizona, United States.
2006 QQ23 is a sub-kilometre asteroid, classified as a near-Earth object of the Aten group that is potentially hazardous only as the orbit evolves over millennia. It was first observed on 21 August 2006 by the Siding Spring Survey. On 10 August 2019, the object safely passed 7.4 million kilometres (4.6 million miles) from Earth. With a 12 year observation arc it has a well determined orbit and is not a threat for the foreseeable future.
2020 PP1 is a sub-kilometer asteroid, classified as a near-Earth object of the Apollo group, that is a temporary quasi-satellite of the Earth. There are over a dozen known Earth quasi-satellites, some of which switch periodically between the quasi-satellite and horseshoe co-orbital states.
2020 SW is a tiny near-Earth asteroid discovered by the Mount Lemmon Survey on 18 September 2020, six days before it made its closest approach to Earth. The asteroid passed within 21,600 kilometres (13,400 mi) from Earth's surface on 24 September 2020 11:13 UT, within the geostationary altitude of 36,000 kilometres (22,000 mi). The encounter with Earth perturbed the asteroid's heliocentric trajectory from an Apollo-type orbit to an Aten-type orbit with a semi-major axis within one astronomical unit from the Sun. As a result, the asteroid will not make any close approaches to Earth within 0.01 astronomical units (4 LD) in the next 200 years.
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