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 0.35% are comets.
(29075) 1950 DA is a risk-listed asteroid, classified as a near-Earth object and potentially hazardous asteroid of the Apollo group, approximately 1.3 kilometers in diameter. It once had the highest known probability of impacting Earth. In 2002, it had the highest Palermo rating with a value of 0.17 and a probability of 1 in 306 (0.33%) for a possible collision in 2880. Since that time, the estimated risk has been updated several times. In December 2015, the odds of an Earth impact were revised to 1 in 8,300 (0.012%) with a Palermo rating of −1.42. As of June 2024, it is listed on the Sentry Risk Table with the highest cumulative Palermo rating of -0.93. 1950 DA is not assigned a Torino scale rating, because the 2880 date is over 100 years in the future. As of 24 April 2024, the odds of an Earth impact reached 1 in 2,600 (0.038%).
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.
(35396) 1997 XF11 (provisional designation 1997 XF11) is a kilometer-sized asteroid, classified as a near-Earth object, Mars-crosser and potentially hazardous asteroid of the Apollo group.
3200 Phaethon, provisionally designated 1983 TB, is an active Apollo asteroid with an orbit that brings it closer to the Sun than any other named asteroid. For this reason, it was named after the Greek myth of Phaëthon, son of the sun god Helios. It is 5.8 km (3.6 mi) in diameter and is the parent body of the Geminids meteor shower of mid-December. With an observation arc of 35+ years, it has a very well determined orbit. The 2017 Earth approach distance of about 10 million km was known with an accuracy of ±700 m.
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.
99942 Apophis (provisional designation 2004 MN4) is a near-Earth asteroid and a potentially hazardous object, 450 by 170 metres in size, that caused a brief period of concern in December 2004 when initial observations indicated a probability 2.7% that it would hit Earth on Friday, 13 April, 2029. Additional observations provided improved predictions that eliminated the possibility of an impact on Earth in 2029. A small possibility nevertheless remained that, during its 2029 close encounter with Earth, Apophis would pass through a gravitational keyhole estimated to be 800 meters in diameter, which would have set up a future impact exactly seven years later on Easter Sunday, April 13, 2036. This possibility kept it at Level 1 on the Torino impact hazard scale until August 2006, when the probability that Apophis would pass through the keyhole was determined to be very small and Apophis's rating on the Torino scale was lowered to zero. By 2008, the keyhole had been determined to be less than 1 km wide. During the short time when it had been of greatest concern, Apophis set the record for highest rating ever on the Torino scale, reaching level 4 on December 27, 2004.
524522 Zoozve (provisional designation 2002 VE68) is a sub-kilometer sized asteroid and temporary quasi-satellite 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.
101955 Bennu (provisional designation 1999 RQ36) is a carbonaceous asteroid in the Apollo group discovered by the LINEAR Project on 11 September 1999. It is a potentially hazardous object that is listed on the Sentry Risk Table and has the highest cumulative rating on the Palermo Technical Impact Hazard Scale. It has a cumulative 1-in-1,750 chance of impacting Earth between 2178 and 2290 with the greatest risk being on 24 September 2182. It is named after Bennu, the ancient Egyptian mythological bird associated with the Sun, creation, and rebirth.
Minimum orbit intersection distance (MOID) is a measure used in astronomy to assess potential close approaches and collision risks between astronomical objects. It is defined as the distance between the closest points of the osculating orbits of two bodies. Of greatest interest is the risk of a collision with Earth. Earth MOID is often listed on comet and asteroid databases such as the JPL Small-Body Database. MOID values are also defined with respect to other bodies as well: Jupiter MOID, Venus MOID and so on.
OSIRIS-REx was a NASA asteroid-study and sample-return mission that visited and collected samples from 101955 Bennu, a carbonaceous near-Earth asteroid. The material, returned in September 2023, is expected to enable scientists to learn more about the formation and evolution of the Solar System, its initial stages of planet formation, and the source of organic compounds that led to the formation of life on Earth. Following the completion of the primary OSIRIS-REx mission, the spacecraft is planned to conduct a flyby of asteroid 99942 Apophis, now as OSIRIS-APEX.
(7482) 1994 PC1 is a stony asteroid and near-Earth object, currently estimated to be the most potentially hazardous asteroid over the next 1000 years. It is in the Apollo group, approximately 1.1 kilometers in diameter. It was discovered on 9 August 1994, by astronomer Robert McNaught at the Siding Spring Observatory in Coonabarabran, Australia. With an observation arc of 47 years it has a very well known orbit and was observed by Goldstone radar in January 1997.
(669555) 2012 YQ1 is a sub-kilometer asteroid, classified as a near-Earth object and a potentially hazardous asteroid of the Apollo group, approximately 200 meters in diameter. It was first observed on 19 December 2012, by astronomers Andrey Oreshko and Timur Kryachko at the Elena Remote Observatory (G32) located in the Chilean Atacama desert.
(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.
469219 Kamoʻoalewa, provisionally designated 2016 HO3, is a very small asteroid, fast rotator and near-Earth object of the Apollo group, approximately 40–100 meters (130–330 feet) in diameter. At present it is a quasi-satellite of Earth, and currently the second-smallest, closest, and most stable known such quasi-satellite (after 2023 FW13). The asteroid was discovered by Pan-STARRS at Haleakala Observatory on 27 April 2016. It was named Kamoʻoalewa, a Hawaiian word that refers to an oscillating celestial object. The object's Earth-like orbit and its composition of lunar-like silicates may be a result of it being lunar ejecta.
(671294) 2014 JO25 is a near-Earth asteroid. It was discovered in May 2014 by astronomers at the Catalina Sky Survey near Tucson, Arizona - a project of NASA's NEO (Near Earth Object) Observations Program in collaboration with the University of Arizona.
Asteroid impact prediction is the prediction of the dates and times of asteroids impacting Earth, along with the locations and severities of the impacts.
2020 LD is an Apollo near-Earth asteroid roughly 140 meters in diameter. It was discovered on 7 June 2020 when the asteroid was about 0.03 AU from Earth and had a solar elongation of 154 degrees. The glare of the Sun had masked the approach of the asteroid since November 2019. The asteroid passed closest approach to Earth on 5 June 2020 at a distance of 0.002 AU. The close approach distance is now known with an accuracy of roughly ± 1000 km. This is the largest asteroid to pass closer than the Moon this year and possibly the largest since (308635) 2005 YU55 in November 2011. The asteroid makes close approaches to Mercury, Venus, Earth, and Mars. It will be brighter than apparent magnitude 24 until 18 July 2020.
(620094) 2016 AJ193 (provisional designation 2016 AJ193; also known as 2010 KV134) is a near-Earth object and potentially hazardous asteroid of the Apollo group, approximately 1.4 kilometres (0.87 mi) in diameter. It was discovered on 17 May 2010 by the Wide-field Infrared Survey Explorer (WISE) satellite, but was lost until it was reobserved on 16 January 2016. With an observation arc over 11 years, 2016 AJ193 has a well-determined orbit and trajectory through the year 2086. The asteroid's orbit is only potentially hazardous on a time scale of thousands of years.
