Amor asteroid

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The Amor asteroids are a group of near-Earth asteroids named after the archetype object 1221 Amor /ˈeɪmɔːr/. The orbital perihelion of these objects is close to, but greater than, the orbital aphelion of Earth (i.e., the objects do not cross Earth's orbit),^[1] 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 (NEAR Shoemaker).

The orbital characteristics that define an asteroid as being in the Amor group are:^[2]

• The orbital period is greater than one year; i.e., the orbital semi-major axis (a) is greater than 1.0 AU (a > 1.0 AU);
• The orbit does not cross that of Earth; i.e., the orbital perihelion (q) is greater than Earth's orbital aphelion (q > 1.017 AU);
• The object is a near-Earth object (NEO); i.e., q < 1.3 AU.

As of October 2024 there are 14,722 known Amor asteroids. Of those objects, 1391 are numbered, 83 are named, and 145 are designated as a potentially hazardous asteroid.^[3][4]

An outer Earth-grazer asteroid is an asteroid that is normally beyond Earth's orbit, but which can get closer to the Sun than Earth's aphelion (1.0167 AU), and not closer than Earth's perihelion (0.9833 AU); i.e., the asteroid's perihelion is between Earth's perihelion and aphelion. Outer Earth-grazer asteroids are split between Amor and Apollo asteroids. Using the definition of Amor asteroids above, "Earth grazers" that never get closer to the Sun than Earth does (at any point along its orbit) are Amors, whereas those that do are Apollos.

To be considered a potentially hazardous asteroid (PHA), an object's orbit must, at some point, come within 0.05 AU of Earth's orbit, and the object itself must be sufficiently large/massive to cause significant regional damage if it impacted Earth. Most PHAs are either Aten asteroids or Apollo asteroids (and thus have orbits that cross the orbit of Earth), and as of November 2023 70 Amors are classified as a PHA, the named objects 2061 Anza, 3122 Florence, 3908 Nyx, and 3671 Dionysus.^[5]

This is a non-static list of named Amor asteroids.^[6]

• List of Amor asteroid records
• Apollo asteroid
• Aten asteroid
• Atira asteroid
• Alinda asteroid
• Arjuna asteroid
• List of minor planets

• List of Amor minor planets