An Etymological Dictionary of Astronomy and Astrophysics

An object having an estimated mass between 1.0 × 10¹⁵ and 4.6 × 10¹⁷ kg, which struck the Earth at the → Cretaceous-Tertiary event about 65 million years ago. It was probably an → asteroid 10 km in diameter with a velocity of roughly 20 km per sec at an angle of just under 60°. The collision
created the → Chicxulub crater. The event was responsible for eliminating approximately 70 percent of all species of animals at or very close to the boundary between the Cretaceous and Paleogene periods.

See also: → Chicxulub crater; → impactor.