Watch the skies for August asteroid In a rare event slated for mid-August, an asteroid will pass close enough to Earth to be visible through binoculars and small telescopes. On Aug. 18, the asteroid will be 327,200 miles (526,600 kilometers) from Earth, according to the Minor Planet Center in Cambridge, Mass. That will put it well beyond the moon�s orbit. The asteroid�s exact size is not known, but it is �somewhat smaller than 1 kilometer (0.62 miles) in diameter,� said Gareth Williams, associate director of the center.