Talk about a close call. NASA says a "relatively large" asteroid will come within a mere 1.1 million miles of our planet tonight. That's a hair's breadth in cosmic terms—only 4.6 times the distance between the earth and the moon, and unusually close for an asteroid this big. Still, NASA stresses that there's no chance of an Armageddon-style collision, which is a relief. The asteroid is named "2014 JO25" and was discovered in 2014. It will be visible in the night sky sometime after April 19 and may even be seen with small optical telescopes for a few nights. NASA has all the details here.
By the way, NASA says the last time this asteroid came this close was at least 400 years ago, so who knows? Maybe Galileo had a gander at this beauty.