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Things to beware of in 1997:
Sudden outbreaks of hostility, racial and otherwise, which seem to
just as suddenly be quelled. Some may notice a fine drizzlelike
mist preceding these events.
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TUCSON, Ariz. -- Viewed through powerful telescopes, comet Hale-Bopp is
already putting on a spectacular light display and astronomers say the best is
still six months away.
"I'm looking forward to a fantastic show in mid-spring," said Harold Weaver,
an astronomer who has been following the progress of Hale-Bopp through the
Hubble Space Telescope.
Weaver said the comet is erupting with bursts of gas every 18 to 26 days as
water is boiled away from its icy core.
"It would look like a sprinkler if you could see it from above," Weaver said
at the national meeting this week of the planetary division of the American
Astronomical Society.
Astronomers have been observing Hale-Bopp for more than a year, and many
observatories are gearing for a major study of the speeding space traveler.
Discovered in July 1995 by amateur astronomers Alan Hale of Stanfield, Ariz.,
and Thomas Bopp of Cloudcroft, N.M., the streaking ball of ice and dust is the
second major comet to pass near Earth in what astronomers have come to call "a
year of the comet."
Last May, the world's telescopes focused on comet Hyakutake. It was the
brightest comet viewed from Earth since the appearance in 1976 of Comet West.
Weaver said that Hale-Bopp is considerably bigger than Hyakutake and may erupt
with 30 times more gas and dust. But Hale-Bopp, in its nearest pass of the
Earth on April 1, will be more than 100 million miles farther away, somewhat
diminishing its light show.
Hale-Bopp appears to be about 18 to 25 miles across, about four times bigger
than Hyakutake, but the new comet is much more energetic in the release of gas.
"This comet is considerably bigger than Haley's, which is considered to be a
large comet," said Weaver.
Astronomers observe comets in different spectrums in order to measure their
chemical content. Gases spewing from the comet and then lighted by the sun
contain chemicals that have specific light signatures.
For taking such data, said Weaver, "Hale-Bopp will be the most productive
comet we have ever measured."
Hale-Bopp is expected to be visible just after sunset in the western sky
starting on April Fools day. It will dip behind the sun after a few days and
not be visible again until August. When it returns to view, however, it will
be more than 200 million miles from Earth and much fainter.
Mike A'Hearn, a University of Maryland astronomer, said that Hyakutake has
"opened up a whole new field of study" because astronomers discovered the
comet was producing X-rays.
X-rays had never before been measured from a comet, but once that radiation
was found with Hyakutake, astronomers reexamined achieved data from earlier
comets. A'Hearn said that X-rays were found to have been produced from five
earlier comets.
Astronomers are still uncertain exactly how the comet produces X-rays, but
A'Hearn said it may be from the collision of clouds of dust erupting from the
comet and the solar wind, the steady stream of radiation from the sun.
A'Hearn said that early studies of Hale-Bopp suggest that the comet is not a
stranger to the neighborhood of the Earth.
"We know the comet has been through the inner solar system hundreds of times,"
said A'Hearn.
He cautioned observers not to be overconfident about just how bright Hale-Bopp
will be from Earth. Some comets in the past have been a great disappointment.
"The predictions are notoriously unpredictable for comets," said A'Hearn.