By Mike Dougherty

PHILADELPHIA (CBS) - More than 1,000 people were injured, mostly from broken glass, when a space rock exploded in the Earth’s atmosphere about 30-40 miles above Russia on Friday.

The chief astronomer at the Franklin Institute, Derrick Pitts, says the latest scientific data available indicates this was a very small asteroid, not a meteor, because it came from the Asteroid Belt.

“I might compare it to a locomotive on a train for the size and mass of the object,” Pitts said. “Since it’s traveling at such a high rate of speed — 40,000 miles per hour — when it comes into contact or interacts with the Earth’s atmosphere, the Earth’s atmosphere is essentially demanding that it slow down.”

When the asteroid hits the brakes, its energy is released.

“That causes the air around it to glow, make it look like it’s burning.”

All leading up to a massive explosion so powerful that it shatters windows up to 50 miles away.

“It has to give up the energy of momentum it has traveling at 40,000 MPH somehow.”

And the asteroid was nearly impossible for astronomers to spot or predict.

“Trying to track objects like this depends upon us being able to see it against a dark night sky. This object came toward Earth out of a daytime sky. We didn’t know it was coming.”

Pitts says NASA has done an excellent job of locating the larger asteroids, which can be hundreds of miles long, but the technology just isn’t there yet to find the small stuff.