http://cosmiclog.msnbc.msn.com/_news/2012/06/21/12344614-that-big-asteroid-was-even-bigger?lite

“The bad news about the asteroid 2012 LZ1, which zipped past Earth last week, is that it’s actually twice as wide and a lot deadlier than we thought — a kilometer (0.6 miles) wide in its largest dimension, rather than 500 meters. The good news is that we have at least seven centuries to figure out how to fight that particular space rock.

“That’s the verdict from astronomers using the 1,000-foot-wide (300-meter-wide) Arecibo Observatory in Puerto Rico, the world’s biggest single radio dish.”

If “they” can be off regarding the size by a factor of 2, it doesn’t leave much confidence in the ability to calculate a tragectory.  At least to me.

Arf