Aten asteroid

[1] The group is named after 2062 Aten, the first of its kind, discovered on 7 January 1976 by American astronomer Eleanor Helin at Palomar Observatory.

As of January 2025, 2,966 Atens have been discovered, of which 271 are numbered, 14 are named, and 197 are classified as potentially hazardous asteroids.

[2][3][4] Aten asteroids are defined by having a semi-major axis (a) of less than 1.0 astronomical unit (AU), the roughly average distance from the Earth to the Sun.

Observation of objects inferior to the Earth's orbit is difficult, and this difficulty may contribute to sampling bias in the apparent preponderance of eccentric Atens.

The shortest semi-major axis for any known Aten asteroid is 0.580 AU, for object 2016 XK24.