The rock, estimated to be no more than 200 feet wide, zoomed past our planet at an altitude of 40,000 miles at 1:44 p.m. universal time — or 8:44 EST.
Dubbed 2009 DD45, it was discovered only on Friday by Australian astronomers.
Forty thousand miles may sound like a lot, but it’s only about one-seventh of the way to the moon, and less than twice as far out as many telecommunications satellites.
Had 2009 DD45 hit the Earth, it would have exploded on or near the surface with the force of a large nuclear blast — not very reassuring when you consider humanity had only about three days’ notice.
If that had hit in the wrong place, it could have made the falling stock market seem like a minor problem.