The Amor asteroids are a group of near-Earth asteroids named after the asteroid 1221 Amor. They approach the orbit of the Earth from beyond, but do not cross it. Most Amors do cross the orbit of Mars. The two moons of Mars, Deimos and Phobos, may be Amor asteroids that were somehow captured by Mars. Computer model of the Apollo Asteroid 6489 Golevka Near-Earth asteroids (NEAs) are asteroids whose orbits are close to Earths orbit. ... 1221 Amor is the namesake of the Amor asteroids, a group of near-Earth asteroids whose orbits range between those of Earth and Mars. ... Deimos (IPA or ; Greek Δείμος: Dread), is the smaller and outermost of Mars’ two moons, named after Deimos from Greek Mythology. ... Phobos (IPA: or [ˈfoʊ.bəs]) (systematic designation: ) is the larger and closer of Mars two moons (the other being Deimos). ...

The most famous member of this group is 433 Eros, which was the first asteroid to be orbited and then landed upon by a human probe (NEAR Shoemaker). The asteroid 433 Eros (eer-os) was named after the Greek god of love Eros. ... Two bodies with a slight difference in mass orbiting around a common barycenter. ... Artists conception of the NEAR Shoemaker spacecraft Near Earth Asteroid Eros as seen from the NEAR spacecraft. ...

Populations

There are over 1200 Amor asteroids known today. Under 200 of them are numbered, and over 50 of them are named.

Subdivisions by semi-major axis

Amor asteroids can be partitioned into four sub-groups, depending on their average distance from the Sun.

Amor I

The Amor I subgroup consists of Amor asteroids whose semi-major axes are in between Earth and Mars. That is, they have a semi-major axis between 1.000 and 1.523 au. Less than one fifth of Amor asteroids belong to this subgroup. Amor I asteroids have lower eccentricities than the other subgroups of Amors. The astronomical unit (AU or au or a. ...

Some Amor I asteroids, such as 15817 Lucianotesi, do not cross the orbit of Mars. They can be considered a part of an Earth-Mars belt. However, not all asteroids located entirely between the orbits of Earth and Mars are Amors.

Amor I asteroids that do cross the orbit of Mars (like 433 Eros), do so from the inside. The asteroid 433 Eros (eer-os) was named after the Greek god of love Eros. ...

Amor I asteroids that have semi-major axes very close to Earth's (such as 1992 JD) can be considered Arjuna asteroids because they have very low eccentricities and thus Earth-like orbits. The Arjuna asteroids are a class of near-Earth asteroids whose orbits are very Earth-like in character, having low inclination, orbital periods close to one Earth year, and low eccentricity. ...

Amor II

The Amor II subgoup has a semi-major axis between that of Mars (1.52 au) and the main asteroid belt (2.12 au). About a third of Amors, including 1221 Amor, belong to this group. They have moderate eccentricities (from 0.17 to 0.52), and all cross the orbit of Mars from the outside. Their orbits usually take them out into the asteroid belt. 1221 Amor is the namesake of the Amor asteroids, a group of near-Earth asteroids whose orbits range between those of Earth and Mars. ... A Mars-crosser asteroid is an asteroid whose orbit crosses that of Mars. ...

Amor III

Almost half of all Amor asteroids lie within the main asteroid belt, and thus have semi-major axes between 2.12 and 3.57 au. These can be considered main belt objects with high enough eccentricities to come near the Earth, usually 0.4 to 0.6.

Because their eccentricities are very large, about a third of Amor III asteroids have orbits that stretch beyond the asteroid belt and come within 1 au of Jupiter. 719 Albert and 1036 Ganymed are two such asteroids. The most extreme Amor III asteroids (such as 5370 Taranis) are actually Jupiter-crossers. 719 Albert is an Amor asteroid, the second one discovered after 433 Eros. ... 1036 Ganymed is the largest Amor asteroid. ... A Jupiter-crosser asteroid is an asteroid whose orbit crosses that of Jupiter. ...

Because they lie within the main asteroid belt, several Amor III asteroids also belong to subgroups of the asteroid belt. For instance, the first Alinda asteroid (in 1:3 resonance with Jupiter and close to a 4:1 resonance with Earth) discovered was 887 Alinda. The Alinda asteroids are a group of asteroids with a semi-major axis of about 2. ... 887 Alinda 887 Alinda is an asteroid orbiting the Sun. ...

Amor IV

There are only a few known Amor asteroids whose average distance from the Sun is beyond the asteroid belt. Their semi-major axes are greater than 3.57 au and they are considered Amor IV asteroids. They are all Jupiter-crossers. Though they have very high eccentricities (0.65 to 0.75), they are not as eccentric as most Damocloids and comets, which tend to have eccentricities around 0.9. The only numbered and named Amor IV asteroid is 3552 Don Quixote. So far, no Amor asteroid has been discovered that crosses the orbit of Saturn. 3552 Don Quixote is a small main belt, Amor, Mars crossing, potentially hazardous asteroid. ... A Saturn-crosser asteroid is an asteroid whose orbit crosses that of Saturn. ...

Cross-populations

Outer Earth-grazer asteroids

An outer Earth-grazer asteroid is an asteroid which is normally beyond the Earth, but which can get closer to the Sun than Earth's aphelion (1.0167 au), but not closer than Earth's perihelion (0.9833 au). In other words, the asteroid's perihelion is between Earth's perihelion and aphelion. Outer Earth-grazer asteroids are split between Amor and Apollo asteroids, depending on the definition you use. A diagram of Keplerian orbital elements. ... A diagram of Keplerian orbital elements. ...

If you use the simple definition of an Amor (1.3000 au > perihelion > 1.0000 au), then asteroids whose perihelion is between 1.0000 au (Earth's semi-major axis) and 1.0167 au (Earth's aphelion) are Amor outer Earth-grazer asteroids, while those between 0.9833 au (Earth's perihelion) and 1.0000 au are considered Apollo outer Earth-grazer asteroids.

If you use the more precise definition of an Amor, those outer Earth-grazers which never get closer to the Sun than the Earth does (at any angle along its orbit) are Amors, and those that do are Apollos. Some "simple" Amor asteroids are also "precise" Apollos, while some "precise" Amors are also "simple" Apollos. Which definition you use is only relevant to outer Earth-grazers.

Potentially hazardous asteroids

Most potentially hazardous asteroids (PHAs) are either Aten asteroids or Apollo asteroids, and therefore cross the orbit of the Earth. However, one tenth of PHAs are Amor asteroids. In order to be considered a PHA, its orbit has to get within 0.05 au from the Earth's orbit and the object has to be "big enough" to be a threat. An Amor asteroid therefore has to have a perihelion of less than 1.05 au to be considered a PHA. About a fifth of Amors come this close to the Sun, and about a fifth of these are actually PHAs. Of the fifty known Amor PHAs, 2061 Anza, 3908 Nyx and 3671 Dionyses have permanent names. A Potentially Hazardous Asteroid (PHA) is a Near-Earth asteroid with an orbit and size that has a potential to make threatening close approaches to the Earth. ... The Aten asteroids are a group of near-Earth asteroids, named after the first of the group to be discovered (2062 Aten, discovered January 7, 1976 by Eleanor F. Helin). ... The Apollo asteroid 25143 Itokawa. ... 3908 Nyx is an Amor and Mars-crosser asteroid. ...

Earth-crossing asteroids

Although, by definition, no Amor asteroid actually currently crosses the Earth's orbit (see Earth-crosser asteroid), the definition of an Earth-crossing asteroid (ECA) is broad enough so that many, if not most, Amor asteroids are also ECAs. An ECA has to be able to some day cross the orbit of the Earth, not just today. If an Amor makes an approach close enough to the Earth, Mars, or Jupiter, it is possible that the gravitational effect of that encounter will alter the asteroid's orbit. Repeated close encounters may eventually cause the planet to cross the Earth's orbit. If astronomers determine that this can happen, the Amor asteroid is classified as an Earth-crossing asteroid. Of course, after its orbit has changed, it will no longer be an Amor asteroid, and will be reclassified as an Apollo asteroid and Earth-crosser asteroid. It can take many years of observation before an asteroid can be classified as an ECA. Diagram showing different asteroid paths. ... An Earth-Crossing Asteroid (ECA), is an asteroid that is capable of coming very near to the Earth at any point in the future. ...

Well-known Amors

3908 Nyx is an Amor and Mars-crosser asteroid. ... Year 1980 (MCMLXXX) was a leap year starting on Tuesday (link displays the 1980 Gregorian calendar). ... Hans-Emil Schuster (born September 19, 1934 in Hamburg) is a German astronomer (retired since October 1991). ... 1221 Amor is the namesake of the Amor asteroids, a group of near-Earth asteroids whose orbits range between those of Earth and Mars. ... Year 1932 (MCMXXXII) was a leap year starting on Friday (the link will display full 1932 calendar) of the Gregorian calendar. ... Eugène Joseph Delporte (January 10, 1882 – October 19, 1955) was a Belgian astronomer. ... 1036 Ganymed is the largest Amor asteroid. ... For the rap album, see 1924 (album). ... Wilhelm Heinrich Walter Baade (March 24, 1893 - June 25, 1960) was a German astronomer who emigrated to the USA in 1931. ... 887 Alinda 887 Alinda is an asteroid orbiting the Sun. ... 1918 (MCMXVIII) was a common year starting on Tuesday of the Gregorian calendar (see link for calendar) or a common year starting on Wednesday of the Julian calendar. ... Maximilian Franz Joseph Cornelius Wolf (June 21, 1863 – October 3, 1932) was a German astronomer. ... 719 Albert is an Amor asteroid, the second one discovered after 433 Eros. ... Year 1911 (MCMXI) was a common year starting on Sunday (link will display the full calendar) of the Gregorian calendar (or a common year starting on Saturday of the 13-day-slower Julian calendar). ... Johann Palisa (December 6, 1848 – May 2, 1925) was an Austrian astronomer, born in Troppau in Austrian Silesia (now in the Czech Republic). ... The asteroid 433 Eros (eer-os) was named after the Greek god of love Eros. ... Year 1898 (MDCCCXCVIII) was a common year starting on Saturday (link will display the full calendar) of the Gregorian calendar (or a common year starting on Monday of the 12-day-slower Julian calendar). ... Carl Gustav Witt (October 29, 1866 – January 3, 1946) was a German astronomer. ...

See also

• Amor asteroids (category)
• List of named Amor asteroids
• Amor asteroid records

Here is a list of all named Amor asteroids. ... The following is a list of current records for Amor_asteroids. ...

External links

• List of Amor minor planets