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 2020, 1841 Atens have been discovered, of which 13 are named. Many Atens are classified as potentially hazardous asteroids.
Lowell Observatory Near-Earth-Object Search (LONEOS) was a project designed to discover asteroids and comets that orbit near the Earth. The project, funded by NASA, was directed by astronomer Ted Bowell of Lowell Observatory in Flagstaff, Arizona. The LONEOS project began in 1993 and ran until the end of February 2008.
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.
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.
The Palomar Planet-Crossing Asteroid Survey (PCAS) was an astronomical survey, initiated by American astronomers Eleanor Helin and Eugene Shoemaker at the U.S Palomar Observatory, California, in 1973. The program is responsible for the discovery of 95 near-Earth Objects including 17 comets, while the Minor Planet Center directly credits PCAS with the discovery of 20 numbered minor planets during 1993–1994. PCAS ran for nearly 25 years until June 1995. It had an international extension, INAS, and was the immediate predecessor of the outstandingly successful NEAT program.
(524522) 2002 VE68, provisional designation 2002 VE68, is a sub-kilometer sized asteroid and temporary quasi-satellite of Venus. It was the first such object to be discovered around a major planet in the Solar System. In a frame of reference rotating with Venus, it appears to travel around it during one Venerean year but it actually orbits the Sun, not 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.
(416151) 2002 RQ25 is a carbonaceous asteroid of the Apollo group, classified as near-Earth object and potentially hazardous asteroid, approximately 0.2 kilometers in diameter. It was discovered on 3 September 2002, by the Campo Imperatore Near-Earth Object Survey (CINEOS) at the Italian Campo Imperatore Observatory, located in the Abruzzo region, east of Rome.
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.
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.
(501647) 2014 SD224 is an Aten near-Earth asteroid around 150 meters (490 feet) in diameter. It was discovered on 22 September 2014 when the asteroid was 0.29 AU (43 million km; 110 LD) from Earth and had a solar elongation of 123 degrees. The glare of the Sun had masked the approach of the asteroid as it passed closest approach to Earth on 11 August 2014. The asteroid now has a 6-year observation arc and a well-determined orbit. It also makes close approaches to Venus.
2020 QG, also known by its internal designation ZTF0DxQ, is an Earth-crossing asteroid, a few meters in diameter. It belongs to the Apollo group, and passed above the surface of Earth approximately 2,950 kilometres (1,830 mi) away on 16 August 2020 at 04:09 UT. It was first imaged by the Zwicky Transient Facility (ZTF) at the Palomar Observatory about 6 hours after this closest approach, and was later identified by Kunal Deshmukh, a student at the Indian Institute of Technology Bombay, along with colleagues Kritti Sharma, Chen-Yen Hsu and Bryce T. Bolin analyzing images from the ZTF.
2020 VT4 is a tiny near-Earth asteroid that passed 370 km (230 mi) above Earth's surface on 13 November 2020 at 17:20 UTC. The asteroid was discovered by the Asteroid Terrestrial-impact Last Alert System (ATLAS) survey at the Mauna Loa Observatory fifteen hours after its closest approach to Earth. The Earth encounter perturbed the asteroid's trajectory from an Earth-crossing Apollo-type orbit to an Aten-type orbit, subsequently reducing the asteroid's heliocentric orbital period from 1.5 years to 0.86 years.
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.
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 expected to be larger than 1 kilometer (0.6 miles) in diameter.
2015 DR215 is a stony near-Earth asteroid of the Atira class residing within Earth's orbit. It was discovered on 18 February 2015 by the Pan-STARRS 1 survey at Haleakalā Observatory at Maui, Hawaiʻi. The asteroid has a diameter of about 200 m (660 ft) and makes close approaches within 0.05 AU (7.5 million km; 4.6 million mi) of Earth, making it a potentially hazardous object. On 11 March 2022, it made a close approach 0.045 AU (6.7 million km; 4.2 million mi) from Earth, reaching a peak apparent magnitude of 17 as it streaked across the southern sky.
