The Apollo asteroids are a group of

near-Earth asteroid 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 aro ...

s named after

1862 Apollo 1862 Apollo is a stony asteroid, approximately 1.5 kilometers in diameter, classified as a near-Earth object (NEO). It was discovered by German astronomer Karl Reinmuth at Heidelberg Observatory on 24 April 1932, but lost and not recovered unti ...

, 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 ...

in the 1930s. They are

Earth-crossing asteroid An Earth-crosser is a near-Earth asteroid whose orbit crosses that of Earth as observed from the ecliptic pole of Earth's orbit. The known numbered Earth-crossers are listed here. Those Earth-crossers whose semi-major axes are smaller than E ...

s that have an orbital

semi-major axis In geometry, the major axis of an ellipse is its longest diameter: a line segment that runs through the center and both foci, with ends at the two most widely separated points of the perimeter. The semi-major axis (major semiaxis) is the longe ...

greater than that of the Earth (a > 1 AU) but

perihelion An apsis (; ) is the farthest or nearest point in the orbit of a planetary body about its primary body. The line of apsides (also called apse line, or major axis of the orbit) is the line connecting the two extreme values. Apsides perta ...

distances less than the Earth's

aphelion An apsis (; ) is the farthest or nearest point in the orbit of a planetary body about its primary body. The line of apsides (also called apse line, or major axis of the orbit) is the line connecting the two extreme values. Apsides perta ...

distance (q < 1.017 AU). , the number of known Apollo asteroids is 21,083, making the class the largest group of

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 ...

s (''cf''. the

Aten Aten, also Aton, Atonu, or Itn (, reconstructed ) was the focus of Atenism, the religious system formally established in ancient Egypt by the late Eighteenth Dynasty pharaoh Akhenaten. Exact dating for the Eighteenth Dynasty is contested, thou ...

, Amor and Atira asteroids), of which 1,742 are numbered (asteroids are not numbered until they have been observed at two or more

oppositions ''Oppositions'' was an architectural journal produced by the Institute for Architecture and Urban Studies from 1973 to 1984. Many of its articles contributed to advancing architectural theory and many of its contributors became distinguished pra ...

), 81 are named, and 2,130 are identified as

potentially hazardous asteroids 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 which is large enough to cause significant regional damage in the Impact event, event ...

. The closer their semi-major axis is to Earth's, the less

eccentricity Eccentricity or eccentric may refer to: * Eccentricity (behavior), odd behavior on the part of a person, as opposed to being "normal" Mathematics, science and technology Mathematics * Off-Centre (geometry), center, in geometry * Eccentricity (g ...

is needed for the

orbit In celestial mechanics, an orbit (also known as orbital revolution) is the curved trajectory of an object such as the trajectory of a planet around a star, or of a natural satellite around a planet, or of an artificial satellite around an ...

s to cross. The

Chelyabinsk meteor The Chelyabinsk meteor () was a superbolide that entered Earth's atmosphere over the southern Ural region in Russia on 15 February 2013 at about 09:20 YEKT (03:20 UTC). It was caused by an approximately , near-Earth asteroid that entered ...

, that exploded over the city of

Chelyabinsk Chelyabinsk; , is the administrative center and largest types of inhabited localities in Russia, city of Chelyabinsk Oblast, Russia. It is the List of cities and towns in Russia by population, seventh-largest city in Russia, with a population ...

in the southern Urals region of Russia on February 15, 2013, injuring an estimated 1,500 people with flying glass from broken windows, was an Apollo-class

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 ...

List

The largest known Apollo asteroid is

1866 Sisyphus 1866 Sisyphus is a binary stony asteroid, near-Earth object and the largest member of the Apollo group, approximately 7 kilometers in diameter. It was discovered on 5 December 1972, by Swiss astronomer Paul Wild at Zimmerwald Observatory n ...

, with a diameter of about 8.5 km. Examples of known Apollo asteroids include:

References

External links

List of Apollo minor planets
{{Small Solar System bodies

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 ...

List

See also

References

External links