This week, a hunk of space rock half the size of a football field will pass historically close to us, between Earth and our communication satellites. Scientists are certain the asteroid, dubbed 2012 DA14, will not hit Earth. If it did, the resulting explosion would equal around 180 Hiroshima atom bombs.

Asteroids have played an immense role in the history of the earth. They may have seeded the earth with organic elements; they wiped out the dinosaurs (which eventually made evolutionary room for humankind); they may even have brought water to the planet.

While nothing is guaranteed, a collision with something like 2012 DA14 isn’t uncommon. Space is like a three-dimensional pool table, with hunks of rock, ice and metal zipping around us all the time. Half a million objects are estimated to inhabit near earth’s orbit alone.

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