Science / Medicine : Researchers Track Closest Asteroid Ever

Researchers using a telescope at the University of Arizona said last week that they have spotted the smallest, closest asteroid ever observed. The asteroid, named 1991 BA, came within 106,000 miles of Earth on Jan. 17, said the team, which reported the sighting to the International Astronomical Union.

“It was a spectacular night, not only because of world events, missiles being lofted on Israel by Iraq, but also because of cosmic events. And it diverted my attention for that evening from the Mideast,” said David Rabinowitz, one of the team’s three principal members.

Rabinowitz and colleague James V. Scotti tracked the asteroid for about six hours “so that we could determine its distance and its orbit.”

The moon is nearly 239,000 miles from the Earth, and Rabinowitz said the asteroid, which they determined to be between 16 1/2 and 33 feet in diameter, came within less than half that distance. “I don’t think anybody’s seen an asteroid come closer than 10 times the distance to the moon.” Also, at only 33 feet across, it’s “at least 10 times smaller than all other known asteroids that have been observed,” Rabinowitz said.