NASA: Asteroid to give Earth close shave

• Space rock is half the size of a football field
• Asteroid will pass 17%2C200 miles above Earth

Close but not too close, a fast-moving asteroid will pass 17,200 miles above Earth on Feb. 15, NASA reports.

The asteroid, 2012 DA14, is a space rock weighing roughly 143,000 tons and measuring 148 feet long, about half the size of a football field. NASA asteroid expert Don Yeomans, author of Near-Earth Objects: Finding Them Before They Find Us, compares the asteroid to the one that leveled hundreds of square miles of Siberian forest in the "Tunguska Event" in 1908.

Only this time Earth won't be hit, the space agency says. Sky watchers might want to keep their eyes peeled that evening as the asteroid should be visible with a backyard telescope. The only problem will be tracking the space rock. It will sail twice the width of the moon across the sky for every minute that it is visible, making it tough to track.