Satellite to Hit Earth Friday—or Fridayish

We know it's coming ... and now we sort of know when. The Upper Atmosphere Research Satellite—the 1,100 pounds of it that make it through Earth’s atmosphere—will crash onto land or sea on Friday. Give or take a day. The Washington Post notes NASA will get more specific as we inch toward the weekend, but even the best estimation will still be a little flimsy. A NASA scientist who specializes in orbital debris says that with two hours until impact, the margin of error will be a sizable 25 minutes. "That equates to plus or minus 5,000 miles. That’s a lot of real estate," he says.

Because so much of Earth is composed of water, the paper notes that UARS will most likely fall into the ocean—there's only a one-in-3,200 chance a chunk will hit somebody, according to NASA's calculations. Another neat thing NASA figured out: The satellite should break into some 100 pieces that will become fireballs, which should be visible even if reentry occurs during the day. Click for more. (More NASA stories.)