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Earth avoids collision with pair of asteroids

A pair of asteroids passed Earth Tuesday and early Wednesday, according to NASA, avoiding a potentially cataclysmic impact with our home planet.

The pair of asteroids — one just over three mile wide — provided both amateur and professional astronomers with an amazing sight. The asteroids, known as ‘2012 XE54’ and ‘4179 Toutatis’ respectively, are some of the largest asteroids to pass by without incident.

2012 XE5, which was discovered just days earlier, passed harmlessly by Earth early late Tuesday and as predicted it was eclipsed by Earth’s shadow, causing its light to appear extinguished for a short time, about 40 minutes. The asteroid passed by Earth, missing our planet by only 139,500 miles or slightly more than half the distance to the moon, according to NASA. The rocky body, estimated at between 50-165 feet across (15-50 meters), allowed astronomers to observe how the rare eclipse appears during flyby.

“Asteroids eclipsing during an Earth flyby are relatively rare, with the first known case of asteroid 2008 TC3 which was totally eclipsed just one hour before entering Earth’s atmosphere over Sudan in 2008, and asteroid 2012 KT42 experiencing both an eclipse and a transit during the same Earth flyby in 2012, ” said Pasquale Tricarico, Ph.D., at the Research Scientist Planetary Science Institute.

Meanwhile, ‘4179 Toutatis, the larger of the two, put on an amazing show for astronomers early Wednesday. The massive asteroid, which missed Earth by 18 lunar lengths, allowed scientists to observe the massive asteroid in detail. Speaking late Tuesday, NASA officials said the asteroid does not pose any danger to Earth, adding that astronomers would examine how Earth’s gravitational field influenced the orbit of the massive space rock.

“At closest approach on December 12th, asteroid 4179 Toutatis will be 7 million km away or 18 times farther than the Moon,” said Lance Benner of NASA’s Near Earth Object Program. “There is no danger of a collision with Earth,” but the asteroid will be close enough for radar imaging.”

Asteroid Toutatis is well known to astronomers, according to NASA.  It passes by Earth’s orbit every four years and astronomers say its unique orbit  means it is unlikely to impact Earth for at least 600 years. Measuring 4.5 km in length, it is one of the largest known potentially hazardous asteroids (PHAs), and its orbit is inclined less than half-a-degree from Earth’s.

“We already know that Toutatis will not hit Earth for hundreds of years,” says Benner.  “These new observations will allow us to predict the asteroid’s trajectory even farther into the future.”

The massive asteroid likely provides astronomers with key data regarding its unusual orbit, which NASA describes as a “poorly thrown football.” Unlike planets and the vast majority of asteroids, which rotate around a single pole, Toutatis has two spin axes. It twirls around one with a period of 5.4 Earth-days and the other once every 7.3 days.

“The result is an asteroid that travels through space tumbling like a badly thrown football,” said one NASA official.