Impact event

An impact event is a collision between astronomical bodies. It can excavate craters, reshape surfaces, and alter the atmospheres or histories of the bodies involved.

Impact cratering: The process by which a high-speed collision excavates and deforms a crater in a solid body's surface. It is the characteristic geological result of an impact on a solid surface.
Chicxulub impactor: The asteroid or cometary body whose collision formed the Chicxulub crater about 66 million years ago. This impact is linked to the end-Cretaceous mass extinction.
Impact hazard: The risk that an astronomical body's collision with Earth will cause damage or loss of life. Assessing this risk requires estimating possible impact frequency and consequences.
Solar System formation: The formation of the Sun and its orbiting bodies from a collapsing cloud of gas and dust. Frequent collisions during this process built planets and left impact scars.
Volcanic crater: A depression formed by volcanic activity, such as an eruption or collapse above a magma chamber. Volcanic craters can resemble impact craters but form through different processes.
Impact velocity: The relative speed of two bodies at the moment they collide. It strongly influences the energy released when the bodies meet.
Shoemaker–Levy 9: A comet that broke apart and struck Jupiter in July 1994. Its fragments made a major planetary impact observable in real time.
Near-Earth object: An asteroid or comet whose orbit brings it close to Earth's orbit. These bodies are monitored because some could collide with Earth.
Planetesimal: A small solid body formed during the early stages of planet formation. Planetesimal collisions helped assemble larger planetary bodies.
Caldera: A large volcanic depression formed when a volcano collapses after magma is withdrawn. Its collapse origin distinguishes it from a depression excavated by a collision.

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