Watch out: Astronomers have spotted a 900-foot-wide asteroid hurtling in the general direction of our feeble little planet. The asteroid is set to fly by on Wednesday, and the good news is it probably won't hit us. (It probably won't even come within 9 million miles of us — about one-tenth the distance of the Earth to the Sun.) But circle your calendars: There remains a small chance that it could collide with Earth when it circles back again in 2036. 

Apophis, as they call it, is named after a mythical Egyptian demon, and is surprising astronomers because it's a lot larger than initially suspected. When it was first spotted in 2004, space watchers calculated that Apophis had an alarmingly high chance of slamming into Earth come 2029 — one in 45, to be specific. Its orbit was recently re-calibrated, however, and experts say it's no longer a threat in 2029.

In 2036, we'll get another chance to catch Apophis up close. This time, there's even a non-negligible chance it'll hit us. Scientists say such a catastrophe likely wouldn't be an "extinction level event," but it could devastate the region of impact and leave a large smoldering scar in the Earth's surface.

So what would we do if a giant space rock really were headed our way? We'd probably have the world's superpowers fire off a few rockets — not to blow the asteroid to smithereens, but to safely nudge it out of orbit.

If you feel so inclined, you can watch humanity's near-brush with doom live via a space camera by Slooh, which culls images from observatories around the world.