Applying unprecedented refinements to the analysis of celestial
hazards, NASA astronomers have identified a potential close
encounter with Earth more than eight centuries in the future by
an asteroid two-thirds of a mile (one kilometer) wide. What will
most likely be a miss, even without preventive measures, will
come on March 16, 2880, said Jon Giorgini, a senior engineer at
NASA's Jet Propulsion Laboratory, Pasadena, Calif. Odds for a
collision are at most one in 300, and probably even more remote,
based on what is known about the asteroid so far. Still, that
makes this space rock, named 1950 DA, a greater hazard than any
other known asteroid. "This is not something to worry about,"
said Giorgini, leader of a team reporting about the asteroid in
the April 5 edition of the journal Science. "We're showing that
searches with optical telescopes and follow-up observations with
radar telescopes can provide us centuries of advance notice
about potential close encounters of asteroids with Earth. That's
plenty of ti