By Dana Ford
Only in space would 2 million miles be considered a close call.
An asteroid with an estimated diameter of three football fields zoomed by Earth late Monday, missing our home by about that distance.
It traveled at some 27,000 miles per hour.
The asteroid came just about a year after a relatively small asteroid blew up over Russia. The roughly 60-foot space rock plunged into Earth's atmosphere and exploded over the city of Chelyabinsk with the force of about 30 early nuclear bombs.
The blast left more than 1,500 injured, mostly by glass from shattered windows, and raised concerns about humanity's vulnerability to stray asteroids.
"On a practical level, a previously unknown, undiscovered asteroid seems to hit our planet and cause damage or injury once a century or so, as we witnessed on June 20, 1908, and February 15, 2013," said Bob Berman, Slooh host and astronomer.
Slooh.com tracks potentially hazardous objects, like asteroids and comets.
Berman added: "Every few centuries, an even more massive asteroid strikes us -- fortunately usually impacting in an ocean or wasteland such as Antarctica.
"But the ongoing threat, and the fact that biosphere-altering events remain a real if small annual possibility, suggests that discovering and tracking all NEOs (near-Earth objects), as well as setting up contingency plans for deflecting them on short notice should the need arise, would be a wise use of resources."
CNN's Matt Smith contributed to this report.
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