The Associated Press 09/15/2011 5:54 AM - LOS ANGELES - A brilliant bright light seen streaking in the night sky over the Southwest was most likely a fireball , a fragment of an asteroid that entered Earth's atmosphere, a NASA scientist said. Residents from Phoenix to Las Vegas to Southern California's coastal areas reported to local authorities and media outlets Wednesday that they saw the light move quickly from west to east at around 7:45 p.m. PDT. Many reported the light as bluish-green and others as yellow and orange. Some captured video of the object. "We can't say 100 percent," said Don Yeomans, manager of NASA's Near-Earth Object Program, "but it's almost certain that the object was a fireball" or very bright meteor, "the size of a basketball or baseball that likely disintegrated before it hit the ground." The bluish-green color suggests the object had some magnesium or nickel in it, Yeomans said. Orange is usually an indication it's entering earth's atmosphere at several miles per second, a moderate rate of speed.