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.
The Amor asteroids are a group of near-Earth asteroids named after the archetype object 1221 Amor. The orbital perihelion of these objects is close to, but greater than, the orbital aphelion of Earth, with most Amors crossing the orbit of Mars. The Amor asteroid 433 Eros was the first asteroid to be orbited and landed upon by a robotic space probe.
Atira asteroids or Apohele asteroids, also known as interior-Earth objects (IEOs), are Near-Earth objects 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.
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.
(612584) 2003 QX113 is a large trans-Neptunian object from the scattered disc located in the outermost region of the Solar System. It is one of the most distant objects from the Sun at 60.5 AU. It was discovered by astronomers with the Canada–France Ecliptic Plane Survey at Mauna Kea Observatories, Hawaii, when it was near aphelion on 31 August 2003. It was provisionally designated 2003 QX113.
(276033) 2002 AJ129, provisional designation 2002 AJ129, is a Mercury-crossing asteroid. It has the ninth-smallest perihelion of all numbered asteroids, after asteroids such as 2000 BD19, 2004 UL, and 2008 XM. It makes close approaches to all of the inner planets and asteroid 4 Vesta. The asteroid is estimated to be between 0.5–1.2 kilometers (0.3–0.7 mi) across. In January 2018 there was much media hype about this asteroid being classified as a potentially hazardous asteroid, although there is no known threat of an impact for hundreds if not thousands of years. The media has compared the size of the asteroid to the Burj Khalifa in Dubai.
(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.
2005 HC4 is the asteroid with the smallest known perihelion of any known object orbiting the Sun (except sungrazing comets). Its extreme orbital eccentricity brings it to within 0.071 AU of the Sun (23% of Mercury's perihelion) and takes it as far as 3.562 AU from the Sun (well beyond the orbit of Mars). Due to its very small perihelion and comparably large aphelion, 2005 HC4 achieves the fastest speed of any known asteroid bound to the Solar System with a velocity of 157 km/s (565,000 km/h; 351,000 mi/h) at perihelion (there are comets, however, which obtain much higher speeds).
2015 KG163, also known as o5m52, is a trans-Neptunian object from the outermost region of the Solar System, approximately 102 kilometers (63 miles) in diameter. It was first observed on 24 May 2015, by astronomers of the Outer Solar System Origins Survey using the Canada–France–Hawaii Telescope at Mauna Kea Observatories, Hawaii, United States. With an observation arc of 2 years, it passed perihelion around August 2022 at a velocity of 6.5 km/s with respect to the Sun.
(574372) 2010 JO179 (provisional designation 2010 JO179) is a large, high-order resonant trans-Neptunian object in the outermost regions of the Solar System, approximately 700 kilometers (430 miles) in diameter. Long-term observations suggest that the object is in a meta-stable 5:21 resonance with Neptune. Other sources classify it as a scattered disc object. It is possibly large enough to be a dwarf planet.
2010 GZ60 was originally estimated by JPL to be a near-Earth asteroid approximately 2 kilometers (1.2 miles) in diameter. But is now known to be an asteroid from the inner region of the asteroid belt that does not get closer than 1.5 AU (220 million km) to Earth.
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.
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.
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.
2020 AP1 is an Apollo near-Earth object roughly 5 meters (20 feet) in diameter. On 2 January 2020 it passed 0.00218 AU (326 thousand km; 0.85 LD) from Earth. With a short 1-day observation arc it was roughly expected to pass about 0.01 AU (1.5 million km; 3.9 LD) from Earth on 7 January 2022, but with an uncertainty of ±8 days for the close approach date it could have passed significantly closer or further.
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.
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.
2021 RR205 is an extreme trans-Neptunian object discovered by astronomers Scott Sheppard, David Tholen, and Chad Trujillo with the Subaru Telescope at Mauna Kea Observatory on 5 September 2021. It resides beyond the outer extent of the Kuiper belt on a distant and highly eccentric orbit detached from Neptune's gravitational influence, with a large perihelion distance of 55.5 astronomical units (AU). Its large orbital semi-major axis (~1,000 AU) suggests it is potentially from the inner Oort cloud. 2021 RR205 and 2013 SY99 both lie in the 50–75 AU perihelion gap that separates the detached objects from the more distant sednoids; dynamical studies indicate that such objects in the inner edge this gap weakly experience "diffusion", or inward orbital migration due to minuscule perturbations by Neptune. While Sheppard considers 2021 RR205 a sednoid, researchers Yukun Huang and Brett Gladman do not.
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.
