Cosmic show to be best in decades
When Halley’s comet was scheduled to make its return visit to the Earth’s vicinity in 1910, astronomers predicted it would come so close that the Earth would pass through the famous comet’s tail.
Alarmed earthlings rushed out and bought gas masks and comet pills to ward off the comet’s evil influence.
And now comes Hale-Bopp, the brightest comet in perhaps 40 years, and the source of a cottage industry of calamitous predictions.
From early claims that the comet would smash into the Earth, to more recent claims that a giant space ship filled with aliens was pacing it, Hale-Bopp has again stirred the imaginations, and paranoia, of humans.
“I guess we haven’t learned much in the last 80 years,” remarked Adam Kremers, a University of Nevada astronomer who does his sky-watching at the university’s Fleischmann Planetarium in Reno. “Every time there is a big comet, people foretold the end of the world.”
First spotted in July, 1995 by two amateur astronomers, the Hale-Bopp comet is already visible to the naked eye, and will grow larger as it makes its closest approach to the sun on April 1. Until March 26, the comet will be visible in the morning sky, but will remain visible in the evening sky for another month or more.
No more than a celestial curiosity to most people these days, comets were often viewed as harbingers of calamity in ancient societies, sometimes linked to the passing of a great leader or to a humiliating military defeat.
But modern interest in comets focuses on what the lumps of ice and rock can tell us about the nature of our solar system and how it began. Astronomers believe that comets are survivors of the solar system’s primordial cloud, existing in a spherical belt beyond the farthest planet, in what is called the Oort Cloud.
The orbits of some make them periodic visitors to the inner solar system, where the sun’s radiation melts and vaporizes part of its ice, forming the comet’s characteristic tail that always points away from the sun. The orbits of some comets are as predictable as clockwork, but others have irregular orbits, or come under the influence of heavy planets like Jupiter, and change their orbits.
“Comets are like cats,” said David Levy, an astronomer who has discovered comets. “They have tails and they do precisely what they want.”
Even though the period of Halley’s orbit is known, how spectacular a show it creates depends on how close the Earth approaches the comet during the comet’s flyby of the sun. In 1910, Halley’s tail covered at least a fourth of the night sky. In 1986, the Earth was farther away, and Halley’s was a mere smudge in the night sky.
Kremers said those who are still alive in 2061, when Halley’s returns, will again be in store for a magnificent show, as the comet will pass much closer to Earth again.
But even Halley’s best show pales in comparison to some historic accounts of comets. In past centuries, comet tails sometimes stretched from one horizon to the other.
As comets go, Hale-Bopp has the potential to be one of the greatest, because its estimated diameter of 25 miles makes it two-to-four times larger than Halley’s. However, Hale-Bopp is expected to circle the sun only once in 4,200 years.
“It’s already brighter than any comet in the last 20 years,” Kremers said. “We don’t know how big it will get, but it may turn out to be the best comet in the last 30 to 40 years. The first week of April, it could put on quite a show.”
Kremers said Hale-Bopp’s intrinsic brightness may be the greatest of any comet since the 14th century.
Compared to the excitement over Hale-Bopp in the scientific community, the comet has been viewed with alarm in the Internet subculture, where unfounded rumors can spread at the speed of light.
First, some astronomy buffs accused NASA of covering up its knowledge that the comet would plow into the Earth. Once enough independent observations dispelled that worry, an amateur astronomer created a sensation by announcing that a photograph revealed an unknown, “Saturn-like object” accompanying Hale-Bopp.
The claim was blown further out of proportion when a firm that conducts “remote viewing” stated that the companion object was a huge UFO. Within weeks, however, the object in the original photograph was identified, and a subsequent photo of the “companion” was declared a fraud by the scientific community.
While the hysteria was brief-lived, Kremers said the concern over a comet or asteroid striking the Earth is no longer considered to be far-fetched.
“Asteroids and comets have hit the Earth in the past, and the odds are getting stronger that the Earth will get struck again sometime in the future.”
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