On February 15th, the asteroid 2012 DA14 will be passing by at the rather intimate distance of 21,500 miles. That’s mighty close: it’s actually within the Clarke orbit used by geosynchronous communication satellites, which circle the planet 22,300 miles up.
It definitely will not hit us, say the boffins, and when it comes to this sort of celestial-mechanics stuff I’m inclined to trust them. (After all, we aren’t talking about climate forecasts here, or Ivy-League economic scapulomancy.)
If you are interested in this sort of thing, you may already know that there are two systems commonly used to assign collision-hazard values to “near-Earth objects”: the “Torino” scale, and the more complex “Palermo” scale. (In case you’re wondering about those names: the Torino scale got its name after it was introduced at a conference there, and the Palermo scale, which came along later, simply carried on the tradition of naming asteroid-hazard scales after populous Italian tourist destinations.) For vastly more information about the Palermo scale, have a look here.
This particular boulder, which is about 150 feet across and weighs something in the order of 130,000 metric tons — that is, roughly equal in size and mass to film-maker Michael Moore — would strike the Earth with an impact equal to a 2.4 megaton bomb. That’s actually pretty paltry compared to some of our more impressive thermonuclear ordnance, and anyway, it’s going to miss us. DA14 has been assigned a zero on the Torino scale, and gets a wimpy Palermo score of -3.19.
So, nothing to worry about, folks, at least this time around. But my sources tell me that there are more than a million of these smallish NEO’s whizzing around, and we only learned about this one just a few months ago. So keep an ear to the ground, or whatever.