A near-Earth object (NEO) is any small Solar System body orbiting the Sun whose closest approach to the Sun (perihelion) is less than 1.3 times the Earth–Sun distance. This definition applies to the object's orbit around the Sun, rather than its current position, thus an object with such an orbit is considered an NEO even at times when it is far from making a close approach of Earth. If an NEO's orbit crosses the Earth's orbit, and the object is larger than 140 meters (460 ft) across, it is considered a potentially hazardous object (PHO). Most known PHOs and NEOs are asteroids, but about a third of a percent are comets.
2006 RH120 is a tiny near-Earth asteroid and fast rotator with a diameter of approximately 2–3 meters that ordinarily orbits the Sun but makes close approaches to the Earth–Moon system around every twenty years, when it can temporarily enter Earth orbit through temporary satellite capture (TSC). Most recently, it was in Earth orbit from July 2006 to July 2007, during which time it was never more than 0.0116 AU (1.74 million km) from Earth. As a consequence of its temporary orbit around the Earth, it is currently the second smallest asteroid in the Solar System with a well-known orbit, after 2021 GM1. Until given a minor planet designation on 18 February 2008, the object was known as 6R10DB9, an internal identification number assigned by the Catalina Sky Survey.
2007 WD5 is an Apollo asteroid some 50 m (160 ft) in diameter and a Mars-crosser asteroid first observed on 20 November 2007, by Andrea Boattini of the Catalina Sky Survey. Early observations of 2007 WD5 caused excitement amongst the scientific community when it was estimated as having as high as a 1 in 25 chance of colliding with Mars on 30 January 2008. However, by 9 January 2008, additional observations allowed NASA's Near Earth Object Program (NEOP) to reduce the uncertainty region resulting in only a 1-in-10,000 chance of impact. 2007 WD5 most likely passed Mars at a distance of 6.5 Mars radii. Due to this relatively small distance and the uncertainty level of the prior observations, the gravitational effects of Mars on its trajectory are unknown and, according to Steven Chesley of NASA's Jet Propulsion Laboratory Near-Earth Object program, 2007 WD5 is currently considered 'lost' (see lost asteroids).
2012 KT42 is an Apollo near-Earth asteroid first observed by astronomer Alex R. Gibbs of the Mount Lemmon Survey with a 1.5-meter reflecting telescope on 28 May 2012.
(471240) 2011 BT15, provisional designation 2011 BT15, is a stony, sub-kilometer sized asteroid and fast rotator, classified as a near-Earth object and potentially hazardous asteroid of the Apollo group. It had been one of the objects with the highest impact threat on the Palermo Technical Impact Hazard Scale.
2014 AA was a small Apollo near-Earth asteroid roughly 2–4 meters in diameter that struck Earth on 2 January 2014. It was discovered on 1 January 2014 by Richard Kowalski at the Mount Lemmon Survey at an apparent magnitude of 19 using a 1.52-meter (60 in) reflecting telescope at Mount Lemmon Observatory. 2014 AA was only observed over a short observation arc of about 70 minutes, and entered Earth's atmosphere about 21 hours after discovery. Nonetheless, it remains one of only a few asteroids observed before impact.
2012 FN is an Apollo asteroid and a near-Earth object that has a 1 in 4 billion chance of impacting Earth on 7 March 2113. It is estimated to be 5 meters in diameter, which means that it poses no threat if it impacts Earth. An impact would have the kinetic energy of about 3 kt of TNT, and would probably result in an air burst in the upper atmosphere. It is the least threatening asteroid listed on the Sentry Risk Table. The very short observation arc of only 3 hours results in a very poorly constrained orbit, and it could just as easily be 2 AU from Earth on 7 March 2113.
(415029) 2011 UL21, provisional designation 2011 UL21, is an Apollo class potentially hazardous asteroid discovered on October 17, 2011, by the Catalina Sky Survey project. The asteroid is estimated to have a diameter of 2.5 kilometres (1.6 mi). It was rated at Torino Scale 1 on October 27, 2011, with an observation arc of 9.6 days.
Asteroid impact prediction is the prediction of the dates and times of asteroids impacting Earth, along with the locations and severities of the impacts.
2019 MO, temporarily designated A10eoM1, was a small, harmless 3-meter near-Earth asteroid discovered by ATLAS–MLO that impacted Earth's atmosphere on 22 June 2019 at 21:25 UT. The impact of the bolide generated a 5-kiloton-equivalent explosion off the south coast of Puerto Rico which was detected by infrasound detectors. The strewn field would be spread over the Caribbean Sea.
2020 BX12 is a sub-kilometer binary asteroid, classified as a near-Earth asteroid and potentially hazardous object of the Apollo group. It was discovered on 27 January 2020 by the Asteroid Terrestrial-impact Last Alert System survey at the Mauna Loa Observatory during its approach to Earth of 0.02915 AU (4.361 million km; 11.34 LD). Radar observations of the asteroid were carried out by the Arecibo Observatory on 4 February 2020, revealing a natural satellite orbiting 360 m (1,180 ft) from the primary body.
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.
2021 UA1 is a small (~2 meter) near-Earth object that passed about 3047 km from the surface of Earth while passing over Antarctica on 25 October 2021 around 03:07 UT. Given the small size of the asteroid it only reached the brightness of Pluto at around apparent magnitude 14. Since it approached from the direction of the Sun, it was not discovered until 4 hours after closest approach.
2022 EB5 was a small, two-metre Apollo near-Earth asteroid that disintegrated in Earth's atmosphere at 21:22 UTC on 11 March 2022, over the Arctic Ocean southwest of the Norwegian island Jan Mayen. With an atmospheric entry speed of 18 km/s (11 mi/s), the asteroid's impact generated a 4-kiloton-equivalent fireball that was detected by infrasound from Greenland and Norway. A bright flash possibly associated with the event was reported by observers from Northern Iceland.
2022 WJ1, formerly designated C8FF042, was a small, harmless ≈1-metre near-Earth asteroid or meteoroid that impacted Earth's atmosphere on 19 November 2022 at 08:27 UT in Southern Ontario, Canada, above the Golden Horseshoe region, southwest of Toronto. Meteorites were detected by weather radar during dark flight.
2022 UR4 is a small near-Earth asteroid that made an extremely close approach within 0.044 lunar distances (17,000 km; 11,000 mi) from Earth's center on 20 October 2022 at 22:45 UTC. It was discovered about 14 hours before closest approach by the Asteroid Terrestrial-impact Last Alert System (ATLAS) survey telescope at Mauna Loa Observatory, Hawaii on 20 November 2022. During the close approach, the asteroid passed above the northern hemisphere of Earth and reached a peak brightness of magnitude 10, just 40 times fainter than the threshold of naked eye visibility.
(741081) 2005 LW3 is a binary near-Earth asteroid classified as a potentially hazardous object of the Apollo group. It was discovered on 5 June 2005 by the Siding Spring Survey at Siding Spring Observatory in Australia. It made a close approach of 2.97 lunar distances (1.14×10^6 km; 0.71×10^6 mi) from Earth on 23 November 2022, reaching a peak brightness of apparent magnitude 13 as it passed over the northern celestial hemisphere sky. It was extensively observed by astronomers worldwide during the close approach, and radar observations by NASA's Goldstone Solar System Radar in California discovered a 100 m (330 ft)-wide natural satellite orbiting the asteroid at a wide separation of 4 km (2.5 mi).
2024 RW1, previously known under its provisional designation CAQTDL2, was a 1-meter-sized asteroid or meteoroid that struck the Earth's atmosphere and burned up harmlessly on September 5, 2024, at around 12:40 a.m. PHT (September 4, 16:40 UTC) above the western Pacific Ocean near Cagayan, Philippines. 2024 RW1 is the ninth impact event that was successfully predicted, which was discovered by Jacqueline Fazekas at NASA-funded Catalina Sky Survey.
2024 XA1, formerly designated as C0WEPC5, is a small meteoroid that fell over eastern Siberia near the city of Olekminsk on 3 December 2024, 16:15 GMT, around 1,000 kilometers east of the Tunguska event impact location. It is the eleventh impact event ever that was successfully predicted, and the fourth in 2024. The impact was witnessed by many people across the Yakutia region of Siberia.
