After passing within 32 million miles of the sun six weeks ago, Comet Austin made its closest approach to the Earth Friday, shimmering in the night sky 22 million miles away. Austin, a massive chunk of ice and dust, has been visible overhead throughout May, appearing as a small fuzzy patch in binoculars or telescopes.
Unlike Comet Halley, which has long been locked into a 76-year orbit of the sun, Austin is thought to be a new visitor to the vicinity of the sun. Most new comets are believed to come from a vast spherical cloud that surrounds the solar system about 4 trillion miles out -- roughly a thousand times as far from the sun as the most distant planet in the solar system. Occasionally this cloud is shaken by some passing gravitational source into a new orbit, which takes it into the inner part of the solar system, close to the sun.
Scientists estimate that Austin's tail, which is created by the sun vaporizing the ice and blowing it away, is at least 2.3 million miles long. Only about 271,000 miles of that is visible from the Earth, however, and the comet itself has turned out to be less spectacular than was originally predicted. There had been hope that Austin would make up for Halley's disappointing show.
"Unfortunately Austin is a bit of a dud," said University of Wisconsin astronomer Christopher Anderson.