Talk about an eventful Friday night! Tomorrow night, a small asteroid will travel nearer Earth than any astronomers have identified beforehand. “It’s the closest that we’ve seen ahead of time,” says Denton Ebel, curator in the Earth and Planetary Sciences.
The Moon is nearly 240,000 miles from Earth, but this asteroid, called 2012 DA14, will travel as close as about 17,200 miles from the planet, over Indonesia. The GIF below was created in 2012, after the asteroid was first observed moving across the sky.
At about 45 meters (150 feet) in diameter, asteroid 2012 DA14 is larger than the astronomers’ estimates of the asteroid that created Meteor Crater in Arizona, notes Ebel. Meteor Crater was formed by an impact thousands of years ago; the crater is about four-fifths of a mile across.
Most asteroids orbit the Sun in the belt between Mars and Jupiter, but others, called near-Earth asteroids, travel in orbits that come closer to our own. Astronomers have tracked about 9,600 of these so far, including asteroid 2012 DA14.
Researchers estimate there are about 500,000 such asteroids, but many have not yet been observed in part because they are small and dark.