ROANOKE TIMES
Copyright (c) 1997, Roanoke Times
DATE: Thursday, January 2, 1997 TAG: 9701020067
SECTION: NATIONAL/INTERNATIONAL PAGE: A-4 EDITION: METRO
SOURCE: Newsday
HALE-BOPP may be the brightest comet seen since 1811 because of all the light-reflecting dust that it's shedding.
Maybe in response to astronomers' chewed nails, crossed fingers and high hopes, a big comet heading in from the outer solar system is performing spectacularly, promising everyone a good look at celestial fireworks come spring.
Although there's still some argument over whether comet Hale-Bopp will rank as ``the comet of the century,'' there's little doubt about the comet's putting on a good show as it makes a pass at the sun, then zooms away into space.
``It's a very large, active comet compared to most of them we see,'' said astronomer Daniel Green, at the Harvard/Smithsonian Center for Astrophysics in Cambridge, Mass. ``It's putting out 10 to 20 times as much gas and dust as comet Halley did at the same distance from the sun.''
Gas and dust are keys to how bright the comet will be as it gets closer and closer to the sun. If it's spewing a lot of dust, it means a lot of sunlight will be reflected, improving the display that will be seen in March and April.
The high level of activity already seen ``gives us confidence to predict it will end up being a real biggie, as productive a comet as we've ever observed,'' said astronomer Harold Weaver of Johns Hopkins University in Baltimore.
Green noted that Hale-Bopp ``is a very dusty comet, as comets go, one of the most dusty we've seen.'' And fortunately, he said, dust reflects sunlight ``right in the middle of the sensitivity of the human eye.'' So the long tail that streams out from the comet should be highly visible in the spring.
The comet, which will make its closest approach to the sun on April1, April Fools' Day, was discovered July23, 1995, by amateur observers Alan Hale of Cloudcroft, N.M., and Thomas Bopp of Phoenix. Since then, it has gained more and more attention as astronomers worldwide watch its progress en route to the sun.
Observations so far, according to astronomer Brian Marsden, show that Hale-Bopp compares very favorably with the great comet of 1811, remembered in part because its arrival coincided with major, memorable events, including Napoleon's attack on Moscow and an extraordinarily good wine year. In the past, comets were feared harbingers of important historical events, including invasions and major disasters.
Marsden, director of the International Astronomical Union's central telegram bureau in Cambridge, said Hale-Bopp is performing so well that ``it should be visible to the naked eye even in polluted [light] areas'' in the spring. In extremely well-lit areas, such as New York City, however, viewing the comet is likely to be difficult.
``Outside the city, it will truly be a naked-eye object,'' visible without the aid of telescopes and binoculars, Weaver said. But he advised that binoculars could be very useful; actually, it's the best way to look at a comet.
``There are limits, but I still think it will be comparable to the great comet of 1811,'' Marsden predicted. ``I think Hale-Bopp is intrinsically brighter, and it will go closer to the sun, inside one astronomical unit.''
An astronomical unit is defined as the Earth's distance from the sun, about 93 million miles.
LENGTH: Medium: 66 linesby CNB