Now that same asteroid is back and about to buzz by us about 70 times closer than it did eight years ago.
Coming closer 2010 WC9 Land will be for data of celestial bodies minimum for the last 300 years. According to calculations at NASA, this will be the asteroid's closest Earth flyby in almost 300 years. While rocky asteroids tend to explode in the atmosphere, such as the asteroid that exploded over Chelyabinsk, if one the size of 2010 WC9 made of iron were to hit the planet, it would leave a crater the size of Meteor Crater west of Winslow, Arizona.
Experts anticipate that the 2010 WC9 asteroid could reach a brightness or magnitude of 11, so although it will not be visible to the naked eye, at least through telescopes pointed at the right place at the right time, it should be sighted moving in front of the stars. Now, imagine the damage that could be done by an asteroid the size of a house entering the atmosphere at more than 45,000 km/h. They lost it in 20 days and were neither able to determine the asteroid's complete orbit nor predict when it might make a comeback. The asteroid 2010 WC9's diameter is somewhere between 60-130 meters. The asteroid injured more than a thousand people in Russian Federation when it exploded and shattered glass in the city, after which it was named. But, persons wishing to see the asteroid can tune in to Slooh, the astronomy broadcasting service beginning at 4 pm Alaska time. The asteroid will move pretty fast (30 seconds of arc per minute). "Our display will update every five seconds", Guy Wells, the founding member of the observatory, told EarthSky.