Asteroids are chunks of rock left over from the formation of our solar system. Approximately half a billion asteroids with sizes greater than four meters in diameter orbit the sun, traveling through our solar system at speeds up to about 30 kilometers per second—about the same speed as Earth.
Asteroids are certainly good at capturing the public imagination. This follows many Hollywood movies imagining the destruction they could cause if a big one hits Earth.
Almost every week we see online headlines describing asteroids the size of a “bus,” “truck,” “vending machine,” “half the size of a giraffe”, or indeed a whole giraffe. We have also had headlines warning of “city killer,” “planet killer” and “God of Chaos” asteroids.
Of course, the threats asteroids pose are real. Famously, about 65 million years ago, life on Earth was brought to its knees by what was likely the impact of a big asteroid, killing off most dinosaurs. Even a four-meter object (half a giraffe, say) traveling at a relative speed of up to 60 kilometers per second is going to pack a punch.
But beyond the media labels, what are the risks, by the numbers? How many asteroids hit Earth and how many can we expect to zip past us?
2023-08-04 23:00:04
Source from phys.org