By JEFF POHJOLA
KIRO Radio

Two large space rocks will come uncomfortably close to earth on Wednesday.

"One of them is called 2010 RX 30, and it's about the size of a small building, which is pretty small for an asteroid. A second asteroid is called 2010 RF 12, a little bit smaller, perhaps the size of an 18 wheeler truck," says NASA's Paul Chodas.

That's considerably smaller than the 6-mile wide object that wiped out the dinosaurs, but still large enough to destroy a city.

Thankfully though, Chodas says neither of them are expected to hit.

"The first one is going to pass over the top of us, over the northern hemisphere, at about two-thirds of the distance of the moon, the second one will be passing even closer, at one-fifth of the distance of the moon, but its passing underneath the earth so it really will only be able to be seen from Antarctica."

The first one should be visible with a basic telescope.