"NASA scientists are saying that an asteroid that appears to be about a third of a mile in size will safely pass about three times the distance of Earth to the moon on Monday."
How close is that?
Said Yeomans: "While it poses no threat to Earth for the foreseeable future, it's a relatively close approach by a relatively large asteroid, so it provides us a unique opportunity to observe and learn more."
In other words, specifically the Hitchhiker's Guide to the Galaxy's: "Don't panic."