We don't mean to scare you, but there is a chance a satellite might fall from the sky, directly onto you this weekend. Oh, who are we kidding? We're definitely trying to freak you out.

NASA's bus-sized Upper Atmospheric Research Satellite is falling to earth this weekend after 20 years and will break into "at least 26 large pieces." OK, but what's the chance that you, personally, will be hit by a space fireball as you walk to brunch on Sunday?

Scientific American's John Matson ran the numbers and there is a 1 in 21 trillion chance that any one person will be hit by the satellite. According to Matson, this is not a very high chance at all:

For a bit of perspective, I am about 14,000 times more likely to be struck dead by lightning on Friday than I am to be struck by UARS. (That estimate is based on rates of fatal U.S. lightning strikes, which show that an average American's risk of being killed by lightning on any given day is about 1 in 1.6 billion.)

But, still! That' s a chance! If the satellite does happen to fall on you, don't panic: just think of it as very suddenly acquiring a large, expensive hat. And you can follow NASA's web site with predictions for its eventual fiery plummet here. [via BoingBoing, photo via Shutterstock.com]