Can asteroids wipe out life?

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Earth has been hit by comets and asteroids in the past, and it will be hit again in the future. But many dangerous space rocks have now been identified and there are ideas for ways to deflect them if needed.

Near miss: Quite often, small asteroids traverse the space between the Earth and the Moon. In many cases, they pass by unnoticed. Most larger potentially hazardous Earth- grazing asteroids have been catalogued by now (artist's impression).
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Our home planet orbits the Sun in a cosmic shooting gallery. While small meteorites are usually harmless, space rocks larger than some 30 metres can wipe out a large city. Asteroids that are one kilometre across can destroy continents and have global climatic effects. A 10-kilometre impactor could kill most species on Earth - as happened to the dinosaurs that became extinct 65 million years ago. Although there are many ideas for protection, mankind is still powerless against large cosmic impacts. But the risk of more frequent smaller asteroid collisions could possibly be mitigated by future technology.

65 million years ago, the dinosaurs died out because of an asteroid impact on Earth. Luckily for us, such large impacts are rare. But we should also worry about smaller cosmic rocks. Maybe we can figure out how to deflect them, so they won't hit the Earth.