Very Small Asteroid Makes Close Earth Approach on February 4, 2011
4 Feb 2011
Asteroid 2011 CQ1 was discovered by the Catalina Sky Survey on February 4 and made a record close Earth approach 14 hours later on February 4 at 19:39 UT (14:39 EST). It passed to within 0.85 Earth radii (5480 km) of the Earth's surface over a region in the mid-Pacific. This object, only about one meter in diameter, is the closest non-impacting object in our asteroid catalog to date. Prior to the Earth close approach, this object was in a so-called Apollo-class orbit that was mostly outside the Earth's orbit. Following the close approach, the Earth's gravitational attraction modified the object's orbit to an Aten-class orbit where the asteroid spends almost all of its time inside the Earth's orbit.
As is evident from the diagram, the close Earth approach changed the asteroid's flight path by about 60 degrees. Because of their small size, object's of this size are difficult to discover but there is likely to be nearly a billion objects of this size and larger in near-Earth space and one would expect one to strike Earth's atmosphere every few weeks on average. Upon striking the atmosphere, small objects of this size create visually impressive fireball events but only rarely do even a few small fragments reach the ground.
Don Yeomans and Paul Chodas
NASA/JPL Near-Earth Object Program Office
February 4, 2011