By Jim Melwert

PHILADELPHIA (CBS) – Scientists say an asteroid will pass closer to Earth today than any other they’ve ever tracked. Though “close” is in cosmic terms, and they say it’s not related to the meteorites in Russia (see related story).

It’s described as being about the size of an apartment building, nearly 50 meters in diameter.

Franklin Institute chief astronomer Derrick Pitts says it will make its closest pass at about 2:30 p.m.

“What makes this really significant is that this is the closest path of an asteroid that’s ever been tracked,” says Pitts. “It’s closest approach will be about 17,150 miles away from Earth,” which sounds like a long way when you consider it’s about 10,000 miles from here to Sydney, Australia.

But, Pitts says, “That’s well within the orbit of the moon. In fact, it’s almost the same altitude as some satellites we have orbiting around the Earth in geo-stationary orbit at 22,300 miles.”

But, again, no danger to Earth, and Pitts says this asteroid will not be visible to us, however the Franklin Institute will have monitors set up with video feeds from NASA for anyone who wants to view the asteroid.

WATCH: NASA Follows Asteroid Flyby

Click here to watch Franklin Institute chief astronomer Derrick Pitts discuss the asteroid.