On the heels of a bus-sized asteroid that passed harmlessly between Earth and the orbit of the Moon on May 13, another asteroid between 4.5 and 10 meters (14-33 feet) wide will buzz by at about the same distance on May 17, 2012.
Asteroid 2012 KA was discovered just today (May 16), and is projected to make its closest approach about 0.0015 AU, or 224,397 kilometers (134,933 miles, .6 lunar distances) from Earths surface at 19:43 UTC on Thursday.
The asteroid was discovered by the Mt. Lemmon Observatory, and at the time of this writing, is the only observatory that has made any observations. Therefore JPL lists the uncertainty of the orbit as fairly high (9 out of a 1 to 10 scale) but orbital projections from JPLs Small Body Database website confirms there is no chance this asteroid would hit Earth.
However, most stony meteoroids up to a diameter of about 10-meters are destroyed in thermal explosions by plummeting through Earths atmosphere.
Explore further: Relief as Russian cargo ship docks at space station