Impact event

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An impact event is the collision of a large meteorite, asteroid, comet, or other celestial object with the Earth or another planet. Throughout recorded history, hundreds of minor impact events (and exploding bolides) have been reported, with some occurrences causing deaths, injuries, property damage or other significant localised consequences.[1] An impact event in an ocean or sea may create a tsunami (a giant wave), which can cause destruction both at sea and on land along the coast.

The latest major impact event occurred in Kaali, Estonia about 700 BC.

Impact events have been a plot and background element in science fiction since knowledge of real impacts became established in the scientific mainstream.


Sizes and frequencies

Small objects frequently collide with the Earth. There is an inverse relationship between the size of the object and the frequency that such objects hit the earth. Asteroids with a 1 km (0.62 mi) diameter strike the Earth every 500,000 years on average.[2] Large collisions – with 5 km (3 mi) objects – happen approximately once every ten million years. The last known impact of an object of 10 km (6 mi) or more in diameter was at the Cretaceous-Tertiary extinction event 65 million years ago.

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