According to NASA, an asteroid some 150-feet wide identified as “2012 DA14” will intersect Earth’s orbit on Friday afternoon (2:24pm EST). This is the closest documented encounter of an asteroid this large (excluding ones which actually smashed into the Earth).
How close? Only about 17,500 miles above our heads. How large? Let’s just say that an asteroid the size of this is capable of blasting a crater (like the one-mile wide hole known as “Meteor Crater” in Arizona) with the equivalent of hundreds of Hiroshima atomic bombs.
Yeah. Take a deep breath, why don’t you?
Several recent asteroids have come closer than DA14 but were much smaller (tens of feet in size). And, when it comes to the consequences of an Earth-asteroid collision, size really matters. Only last December a somewhat smaller asteroid, XE54, passed within about 140,000 miles of Earth, and was about as close to crashing into Earth as an asteroid can without actually doing so.
Phew. Close call! It’s alright peeps. We’re safe.
(Source)