A huge asteroid will have a close encounter with Earth this weekend, but astronomers say there is no danger of an impact. The asteroid, known as 2004 XP14, will whiz by about 269,000 miles (432,821 kilometers) from the Earth, about 1.1 times farther away than the moon. Astronomers know little about the asteroid, which was discovered in 2004. But it is estimated to be as large as a half-mile wide based on its brightness. More than three dozen asteroids have flown closer to Earth in the last few years, but scientists say 2004 XP14 is one of the largest to zip by. "For something of this size to come this close is unusual," said Don Yeomans, who heads the Near Earth Object Program at NASA's Jet Propulsion Laboratory. "It's not Earth-threatening," Yeomans said.