Asteroid to pass close to Earth's surface

Bill Logan / For The Bulletin /

Published Feb 6, 2013 at 04:00AM

On Feb. 15, an asteroid, about 50 yards wide, will fly past Earth at only 17,200 miles above our planet’s surface. While a collision with Earth does not appear imminent, the space rock, designated 2012 DA14, has NASA’s attention.

“This is a record-setting close approach,” said Don Yeomans of NASA’s Near Earth Object Program at JPL, in a statement. “Since regular sky surveys began in the 1990s, we’ve never seen an object this big (fly) so close to Earth.”

Asteroid 2012 DA14 is probably made of stone, as opposed to metal or ice. Yeomans estimated that an asteroid like this flies past Earth, on average, every 40 years, yet actually strikes our planet about every 1,200 years.

Yeomans pointed out that a similar-sized object formed the mile-wide Barringer Meteor Crater in Winslow, Ariz., when it struck about 50,000 years ago. “That asteroid was made of iron,” he said, “which made it an especially potent impactor.” Also, in 1908, something about the size of 2012 DA14 exploded in the atmosphere above Siberia, leveling hundreds of square miles of forest. Researchers are still studying the Tunguska event for clues.

NASA radar will be monitoring the space rock as it approaches closer than many man-made satellites. Yeomans said, “The asteroid will thread the gap between low-Earth orbit, where the (International Space Station) and many Earth observation satellites are located, and the higher belt of geosynchronous satellites, which provide weather data and telecommunications.” The odds of an impact with a satellite are extremely remote, he said. Almost nothing orbits where DA14 will pass the Earth.

During the hours around closest approach, the asteroid will brighten until it resembles a star of eighth magnitude. The problem, Yeomans said, is speed. “The asteroid will be racing across the sky, moving almost a full degree (or twice the width of a full moon) every minute. That’s going to be hard to track.” Only the most experienced amateur astronomers are likely to succeed.

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— Bill Logan is an expert solar observer and a volunteer amateur astronomer with University of Oregon’s Pine Mountain Observatory. He lives in Bend. Contact: