Asteroid approaching for Earth fly-by found to have its own 'moon'

PASADENA, Calif., May 30 (UPI) -- An asteroid that will pass by Earth Friday is in fact a binary asteroid, with a smaller asteroid orbiting a larger one like a small moon, U.S. astronomers say.

A sequence of radar images of asteroid 1998 QE2 suggest the main body, or primary, is around 1.7 miles in diameter while a preliminary estimate for the width of the asteroid's satellite, or moon, is approximately 2,000 feet.

The closest approach of the asteroid pair will occur Friday at 1:59 4:59 p.m. EDT, when they will pass Earth no closer than about 3.6 million miles or about 15 times the distance between Earth and the moon, NASA's Jet Propulsion Laboratory in Pasadena, Calif., reported.

Binary asteroids are not uncommon, astronomers said; in the near-Earth population about 16 percent of asteroids of about 655 feet or larger are part of binary or even triple systems.

The sequence of radar images of asteroid 1998 QE2 was obtained Wednesday by NASA scientists using the 230-foot Deep Space Network antenna at Goldstone, Calif., when the asteroid was about 3.75 million miles from Earth, JPL said.