1862 Apollo is a stony

asteroid An asteroid is a minor planet—an object larger than a meteoroid that is neither a planet nor an identified comet—that orbits within the Solar System#Inner Solar System, inner Solar System or is co-orbital with Jupiter (Trojan asteroids). As ...

, approximately 1.5 kilometers in diameter, classified as a

near-Earth object 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 (astronomical unit, AU). This definition applies to the object's orbit a ...

(NEO). It was discovered by German astronomer

Karl Reinmuth Karl Wilhelm Reinmuth (4 April 1892 in Heidelberg – 6 May 1979 in Heidelberg) was a German astronomer and a prolific discoverer of 395 minor planets. Scientific career From 1912 to 1957, Reinmuth was working as an astronomer at the He ...

Heidelberg Observatory Heidelberg (; ; ) is the List of cities in Baden-Württemberg by population, fifth-largest city in the States of Germany, German state of Baden-Württemberg, and with a population of about 163,000, of which roughly a quarter consists of studen ...

on 24 April 1932, but lost and not recovered until 1973. It is the namesake and the first recognized member of the Apollo asteroids, a subgroup of NEOs which are Earth-crossers, that is, they cross the orbit of the Earth when viewed perpendicularly to the ecliptic plane (crossing an orbit is a more general term than actually intersecting it). In addition, since Apollo's orbit is highly eccentric, it crosses the orbits of Venus and Mars and is therefore called a Venus-crosser and Mars-crosser as well. Although Apollo was the first Apollo asteroid to be discovered, its official IAU-number (1862) is higher than that of some other Apollo asteroids such as 1566 Icarus, because it was a lost asteroid for more than 40 years and other bodies were numbered in the meantime. The analysis of its rotation provided observational evidence of the YORP effect. It is named after the Greek god

Apollo Apollo is one of the Twelve Olympians, Olympian deities in Ancient Greek religion, ancient Greek and Ancient Roman religion, Roman religion and Greek mythology, Greek and Roman mythology. Apollo has been recognized as a god of archery, mu ...

. He is the god of the Sun, child of Zeus and Leto, after which the minor planets 5731 Zeus and

68 Leto 68 Leto is a large main belt asteroid that is orbiting the Sun. The asteroid was discovered by German astronomer Robert Luther on April 29, 1861, and is named after Leto, the mother of Apollo and Artemis in Greek mythology. It orbits at a dist ...

are named.

Satellite

On November 4, 2005, it was announced that an

asteroid moon A minor-planet moon is an astronomical object that orbits a minor planet as its natural satellite. , there are 457 minor planets known or suspected to have moons. Discoveries of minor-planet moons (and binary objects, in general) are important ...

, or satellite of Apollo, had been detected by radar observations from

Arecibo Observatory The Arecibo Observatory, also known as the National Astronomy and Ionosphere Center (NAIC) and formerly known as the Arecibo Ionosphere Observatory, is an observatory in Barrio Esperanza, Arecibo, Puerto Rico owned by the US National Science F ...

Puerto Rico ; abbreviated PR), officially the Commonwealth of Puerto Rico, is a Government of Puerto Rico, self-governing Caribbean Geography of Puerto Rico, archipelago and island organized as an Territories of the United States, unincorporated territo ...

, October 29 – November 2, 2005. The announcement is contained in the

International Astronomical Union The International Astronomical Union (IAU; , UAI) is an international non-governmental organization (INGO) with the objective of advancing astronomy in all aspects, including promoting astronomical research, outreach, education, and developmen ...

Circular (IAUC) 8627. The satellite is only across and orbits Apollo just away from the asteroid itself. From the surface of Apollo, S/2005 (1862) 1 would have an angular diameter of about 2.0835 degrees.Calculated from the formula

\delta

= (206265) ''d'' / ''D'' arcseconds. (see

Angular diameter The angular diameter, angular size, apparent diameter, or apparent size is an angular separation (in units of angle) describing how large a sphere or circle appears from a given point of view. In the vision sciences, it is called the ''visual an ...

)

Potentially hazardous object

1862 Apollo is a potentially hazardous asteroid (PHA) because its

minimum orbit intersection distance 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 o ...

(MOID) is less than 0.05 AU and its diameter is greater than 150 meters. Apollo's Earth MOID is . Its orbit is well-determined for the next several hundred years. On 17 May 2075 it will pass from

Venus Venus is the second planet from the Sun. It is often called Earth's "twin" or "sister" planet for having almost the same size and mass, and the closest orbit to Earth's. While both are rocky planets, Venus has an atmosphere much thicker ...

Satellite

Potentially hazardous object

See also

Notes

References

External links