Apollo asteroid

They are Earth-crossing asteroids that have an orbital semi-major axis greater than that of the Earth (a > 1 AU) but perihelion distances less than the Earth's aphelion distance (q < 1.017 AU).

[1][2] As of January 2025[update], the number of known Apollo asteroids is 21,083, making the class the largest group of near-Earth objects (cf.

[4][5] The closer their semi-major axis is to Earth's, the less eccentricity is needed for the orbits to cross.

The Chelyabinsk meteor, that exploded over the city of Chelyabinsk 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.

[6][7] The largest known Apollo asteroid is 1866 Sisyphus, with a diameter of about 8.5 km.