Every 76 years, planet Earth is visited by what scientist Fred Whipple of Harvard calls ``that big dirty snowball in the sky'' -- Halley's comet. As a matter of fact, Halley is a 100 billion-ton dirty snowball. Recorded first in China in 240 BC, it visited last in 1910 and is coming again in 1985-86. Last time there was a lot of speculation and fear, some scientific observation, but very little use made of the information collected. This time, despite the fact that the United States does not have a Halley's probe (that research is being done by the European, Soviet, and Japanese space agencies), just about every observatory in the world is focusing on Halley's comet as it swings by.
According to narrator James Earl Jones of Comet Halley (PBS, Tuesday, Nov. 26, 9-10 p.m., check local listings), ``Never before in history has a single celestial object been the subject of such universal scrutiny.'' One spacecraft will fly within 300 miles of the comet's nucleus. Scientists are hoping to learn something about the origin of the solar system and perhaps find clues to the origin of life on Earth.
``Comet Halley'' is basically a prep course for the Close Encounter. Besides briefing viewers who aren't astrology buffs on the history of the comet and the story of royal astronomer Halley, the documentary provides tips on what kind of telescope to buy, where to watch, what to watch for, and how to greet that ``old friend who comes back for a visit every 76 years.''
To see it best, starting around Jan. 1 and through mid-March, go as far south as possible, away from cities, on nights without a moon or else early in the morning.
According to producers John L. Wilhelm of WETA, Washington, D.C., and Asahi Broadcasting Corporation of Japan, you have only around one-quarter of a million years left to see the comet. Next time will be in the year 2061.
Major underwriters for the Halley special are, would you believe, Milky Way and Mars Bars. Opportunistic commercialization of space? Well, it's only once every 76 years.