By Casey Frye, CCNN Writer
This past weekend, a bus-sized asteroid large enough to destroy a small city cruised by Earth. It zipped by within 186,000 miles, which is pretty close as far as near-Earth asteroids go, and came nearer than the Moon which is about 240,000 miles away. It was first spotted way out in space on April 28, and swooped by us on Saturday.
There are millions of asteroids, and most of the ones we know about orbit in the asteroid belt that’s between Mars and Jupiter. The ones that can come close to our planet are called near-Earth asteroids, and there’s over 10,000 of them that we’ve discovered so far.
Fortunately, only about 981 are 1 kilometer in diameter, and these mega destroyers hit Earth an average of two times every million years.
Even smaller ones can be devastating when they strike Earth, though. In fact, if they’re 7 meters wide, they can enter our atmosphere with the power of the atomic bomb dropped on Hiroshima, Japan by the USA in World War II.
That might sound scary, but most of them get eaten up in the atmosphere, exploding into tiny pieces that burn out before reaching us. Still, NASA and the United Nations aren’t taking any chances, and have been working on an asteroid defense plan.
Images courtesy of NASA.