Mysterious light over Southwest likely a fireball

[September 16, 2011]  LOS ANGELES (AP) -- A brilliant light seen darting across the Southwest night sky was most likely a piece of asteroid that entered Earth's atmosphere, a NASA scientist said Thursday.

Scores of people from Southern California to Arizona reported to local authorities and media outlets Wednesday that they saw the light hurtle quickly from west to east at around 7:45 p.m. PDT. Many described the light as bluish-green and others as yellow and orange. Some captured video of the object.

Don Yeomans, who heads NASA's Near-Earth Object Program, said he was convinced it was a fireball -- a fragment of an asteroid the size of a baseball or basketball that hit the atmosphere and disintegrated before reaching the ground.

This natural phenomenon tends to happen on a weekly basis, but usually occurs over the ocean where no one can see.

"It's unusual for an object of this size to be seen over populated areas," Yeomans said.

After witnessing the bright streak of light, sky watchers took to Twitter to speculate what it could be.

Yeomans said the explanation is mundane. The bluish-green color suggests the object had some magnesium or nickel in it. Orange is usually an indication it's entering the atmosphere at several miles per second, a moderate rate of speed.

"It's one of Mother Nature's better light shows," Yeomans said.

Yeomans ruled out a dead spacecraft falling back to Earth because such events can be predicted ahead of time. Federal Aviation Administration spokesman Ian Gregor confirmed that there were no aircraft incidents reported in the western region.

[Associated Press; By DENISE PETSKI]

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