Asteroids

The asteroid will come nearly as close as our moon in one of the closest encounters in a decade.

"To protect Earth from potentially hazardous impacts, we need to understand asteroids much better."

It's harmless, but consider it a reminder of the threat posed by space rocks

Buried beneath the rocks, dirt, buildings and roads of the city of Decorah, Iowa, lies a 470 million-year-old meteorite crater. Unlike the craters on the pockmarked surfaces of the moon and Mars, this crater can't be seen by looking down at Earth's surface, at least not by the human eye.