A near-Earth object (NEO) is any small Solar System body whose orbit brings it into proximity with Earth. By convention, a Solar System body is a NEO if its closest approach to the Sun (perihelion) is less than 1.3 astronomical units (AU). If a 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 a small fraction are comets.
(29075) 1950 DA, provisional designation 1950 DA, is a risk–listed asteroid, classified as a near-Earth object and potentially hazardous asteroid of the Apollo group, approximately 1.1 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 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 2022, It is listed on the Sentry Risk Table with the second highest cumulative Palermo rating of −2.05. 1950 DA is not assigned a Torino scale rating, because the 2880 date is over 100 years in the future.
Asteroid impact avoidance comprises the methods by which near-Earth objects (NEO) on a potential collision course with Earth could be diverted away, preventing destructive impact events. An impact by a sufficiently large asteroid or other NEOs would cause, depending on its impact location, massive tsunamis or multiple firestorms, and an impact winter caused by the sunlight-blocking effect of large quantities of pulverized rock dust and other debris placed into the stratosphere. A collision 66 million years ago between the Earth and an object approximately 10 kilometres wide is thought to have produced the Chicxulub crater and triggered the Cretaceous–Paleogene extinction event that is understood by the scientific community to have caused the extinction of all non-avian dinosaurs.
SETI@home is a project of the Berkeley SETI Research Center to analyze radio signals, searching for signs of extraterrestrial intelligence. Until March 2020, it was run as an Internet-based public volunteer computing project that employed the BOINC software platform. It is hosted by the Space Sciences Laboratory at the University of California, Berkeley, and is one of many activities undertaken as part of the worldwide SETI effort.
The Berkeley Open Infrastructure for Network Computing is an open-source middleware system for volunteer computing. Developed originally to support SETI@home, it became the platform for many other applications in areas as diverse as medicine, molecular biology, mathematics, linguistics, climatology, environmental science, and astrophysics, among others. The purpose of BOINC is to enable researchers to utilize processing resources of personal computers and other devices around the world.
(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.
1566 Icarus is a large near-Earth object of the Apollo group and the lowest numbered potentially hazardous asteroid. It has is an extremely eccentric orbit (0.83) and measures approximately 1.4 km (0.87 mi) in diameter. In 1968, it became the first asteroid ever observed by radar. Its orbit brings it closer to the Sun than Mercury and further out than the orbit of Mars, which also makes it a Mercury-, Venus-, and Mars-crossing asteroid. This stony asteroid and relatively fast rotator with a period of 2.27 hours was discovered on 27 June 1949, by German astronomer Walter Baade at the Palomar Observatory in California. It was named after the mythological Icarus.
69230 Hermes is a sub-kilometer sized asteroid and binary system on an eccentric orbit, classified as a potentially hazardous asteroid and near-Earth object of the Apollo group, that passed Earth at approximately twice the distance of the Moon on 30 October 1937. The asteroid was named after Hermes from Greek mythology. It is noted for having been the last remaining named lost asteroid, rediscovered in 2003. The S-type asteroid has a rotation period of 13.9 hours. Its synchronous companion was discovered in 2003. The primary and secondary are similar in size; they measure approximately 810 meters (2,700 ft) and 540 meters (1,800 ft) in diameter, respectively.
Catalina Sky Survey is an astronomical survey to discover comets and asteroids. It is conducted at the Steward Observatory's Catalina Station, located near Tucson, Arizona, in the United States.
The MIT Lincoln Laboratory, located in Lexington, Massachusetts, is a United States Department of Defense federally funded research and development center chartered to apply advanced technology to problems of national security. Research and development activities focus on long-term technology development as well as rapid system prototyping and demonstration. Its core competencies are in sensors, integrated sensing, signal processing for information extraction, decision-making support, and communications. These efforts are aligned within ten mission areas. The laboratory also maintains several field sites around the world.
99942 Apophis is a near-Earth asteroid and potentially hazardous asteroid with a diameter of 370 metres that caused a brief period of concern in December 2004 when initial observations indicated a probability up to 2.7% that it would hit Earth on April 13, 2029. Additional observations provided improved predictions that eliminated the possibility of an impact on Earth in 2029. Until 2006, a small probability nevertheless remained that, during its 2029 close encounter with Earth, Apophis would pass through a gravitational keyhole of no more than about 800 metres in diameter, which would have set up a future impact exactly seven years later on 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' 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.
Wide-field Infrared Survey Explorer is a NASA infrared astronomy space telescope in the Explorers Program. It was launched in December 2009, and placed in hibernation mode in February 2011, before being re-activated in 2013 and renamed the Near-Earth Object Wide-field Infrared Survey Explorer (NEOWISE). WISE discovered thousands of minor planets and numerous star clusters. Its observations also supported the discovery of the first Y-type brown dwarf and Earth trojan asteroid.
3122 Florence is a stony trinary asteroid of the Amor group. It is classified as a near-Earth object and potentially hazardous asteroid. It measures approximately 5 kilometers in diameter. It orbits the Sun at a distance of 1.0–2.5 AU once every 2 years and 4 months ; the orbit has an eccentricity of 0.42 and an inclination of 22° with respect to the ecliptic. Florence has two moons.
A potentially hazardous object (PHO) is a near-Earth object – either an asteroid or a comet – with an orbit that can make close approaches to the Earth and is large enough to cause significant regional damage in the event of impact. They are defined as having a minimum orbit intersection distance with Earth of less than 0.05 astronomical units and an absolute magnitude of 22 or brighter. More than 99% of the known potentially hazardous objects are not an impact threat over the next 100 years. As of September 2022, only 17 potentially hazardous objects are listed on the Sentry Risk Table as objects that are known not to be a threat over the next hundred years are excluded. Over hundreds if not thousands of years, "potentially hazardous" asteroids have the potential for their orbits to evolve to live up to their namesake.
(136617) 1994 CC is a sub-kilometer trinary asteroid, classified as near-Earth object and potentially hazardous asteroid of the Apollo group.
NEO Surveyor, formerly called Near-Earth Object Camera (NEOCam), then NEO Surveillance Mission, is a planned space-based infrared telescope designed to survey the Solar System for potentially hazardous asteroids.
The Asteroid Terrestrial-impact Last Alert System (ATLAS) is a robotic astronomical survey and early warning system optimized for detecting smaller near-Earth objects a few weeks to days before they impact Earth.
(86039) 1999 NC43, is an asteroid on an eccentric orbit, classified as near-Earth object and potentially hazardous asteroid of the Apollo group, approximately 2 kilometers in diameter. This suspected tumbler and relatively slow rotator was discovered by LINEAR in 1999.
2013 ND15 (also written 2013 ND15) is an asteroid that is a temporary trojan of Venus, the first known Venus trojan.
A temporary satellite is an object which has been captured by the gravitational field of a planet and thus has become the planet's natural satellite, but, unlike irregular moons of the larger outer planets of the Solar System, will eventually either leave its orbit around the planet or collide with the planet. The only observed examples are 2006 RH120, a temporary satellite of Earth for twelve months from July 2006 to July 2007, and 2020 CD3, which was discovered in 2020. Some defunct space probes or rockets have also been observed on temporary satellite orbits.
