A newly discovered asteroid should zoom past Earth June 27, posing no threat to the planet but significantly bending the orbital path of the asteroid [see orbital diagram at left].

The space rock, known as 2011 MD, was first detected on June 22 by the Lincoln Near Earth Asteroid Research (LINEAR) project at a telescope in New Mexico. Based on how much sunlight it reflects, 2011 MD is estimated to be five to 20 meters in diameter, according to the Web site of the Near-Earth Object (NEO) Program Office at the NASA Jet Propulsion Laboratory in Pasadena, Calif.

2011 MD is expected to pass over the Southern Hemisphere at an altitude of about 12,000 kilometers at 1:00 P.M. (Eastern Daylight Time). That will bring the asteroid within the orbit of some high-altitude satellites, although the chance of a collision is vanishingly small. Asteroids frequently buzz the planet, often undetected, but the increased capabilities of asteroid-spotting searches in the past several years has made it more common that smallish asteroids such as 2011 MD are discovered before their planetary flybys. "One would expect an object of this size to come this close to Earth about every six years on average," Don Yeomans and Paul Chodas of NASA's NEO Program Office wrote on the program's Web site.

Orbit diagram of 2011 MD: NASA/JPL