Asteroid Passes Earth
An asteroid half the size of a football field has passed closer to Earth than any other known object of its size.
It occurred on the same day that an unrelated and much smaller space rock blazed over central Russia.
Asteroid 2012 DA14, discovered just last year, passed about 27,700 km from Earth on Friday.
It came closer to Earth than many communication and weather satellites.
Flybys like this one occur only once in every 40 years.
SOUNDBITE(ENGLISH) DANTE LAURETTA, Arizona University:
"The flyby of asteroid 2012 DA14 is an historic event. Never before in human history have we been able to see an object come this close this size. "
In a coincidence, a meteor exploded above Russia's Ural Mountains just hours before the asteroid zoomed past the planet.
The space rock was thought to have weighed nearly 10 tons.
It created a shockwave that blew out windows and collapsed some walls, leaving more than 1,000 people injured.
Scientists the world over insisted the meteor had nothing to do with the asteroid since they appeared to be traveling in opposite directions.