again. >> that's right. a big space rock the size of a city block is expected to buzz by us at this hour. >> don't worry, there's no danger of it hitting us. the closest it will come to earth, about 605,000 miles. we're good. about 2 1/2 times the distance from the earth to the moon. joining us for more, alexandria steele and lawrence krause, the author of the book "a universe from nothing." alexandra, let's start with you. how big is this compared to some other recent space rocks in the news like the one that hit russia last month. will we be able to see this with the naked eye? >> oh, absolutely not. it's too faint, too far, you can't see it. the closest pass is coming right now. you can't see it, though, with the telescope in your backyard. a lot of the east coast has good visibility, but it's not possible. it is the size of a football field. it's called 2013et, only