"Amid all the progress on this planet -- declining losses from terrible diseases and war, rising literacy and the rest -- there remain plenty of planet-scale risks requiring serious focus, from pandemic flu to centuries of locked-in climate change to, yes, collisions with space rocks."
"This week provides another reminder of the reality of that threat, not that Earth’s history doesn’t already provide plenty of warnings. Bill Marsh, an illustrator at The Times, created the illuminating chart above (the image is a detail; click for the full graphic) to show just how close the asteroid known as 2012 DA14 will come on Friday. It will pass not only far inside the orbit of the Moon, but even closer than the 22,300-mile distance where geosynchronous satellites orbit.
I was fortunate to participate in a 2010 workshop assessing what kinds of protocols should be developed to coordinate international responses when astronomers finally identify an object that will hit Earth. A report from that meeting, 'Responding to the Threat of Potentially-Hazardous Near Earth Objects,' provides a primer on both the risk and possible responses."