Forget the letdown of Halley's Comet in 1986. Even Comet Hyakutake, which thrilled many stargazers last year, didn't come close to offering the kind of brilliant celestial show that Hale-Bopp does.
"This is your classic comet. This is the one that's going to look like the photos in the books," said Rodney Martin, planetarium resources teacher for the Washington County Board of Education.
Compared to the planets, their moons and the sun, comets are relative atomic particles. Hale-Bopp's nucleus of ice and dirt, formed in the cold, distant regions of the solar system, is believed to be just 25 miles wide.
But as a comet orbits closer to the sun, some of its particles vaporize, causing it to be shrouded in a giant cloud of gas, called a coma, and a tail of exhaust that extends for millions of miles. Hale-Bopp's coma is about 100,000 miles wide. Its tail stretches for 100 million miles, Martin said.
"That's why it's so easy to see," Martin said.
Comets are fickle, and it's impossible for scientists to predict how spectacular they will appear ahead of time. They are affected by a variety of conditions, including their size, composition and where they have previously traveled.
"Each one has slightly different characteristics about it," said C.J. Warner Jr., an amateur astronomer in Waynesboro, Pa.
In many cases they merely appear like faint, fuzzy stars - as Halley did in '86 - and are barely detectable to the naked eye. Rarer are Comet Bennett (1970), Comet West (1976) and now Comet Hale-Bopp, which are considered among the century's best.
"Comets have a mind of their own, and you never know exactly what they are going to do," said Adam Stachura, assistant producer for the Davis Planetarium at the Maryland Science Center in Baltimore.
But scientists had a pretty good feeling about Hale-Bopp, mostly because it was discovered two years ago when it was still beyond Jupiter, some 577 million miles from Earth.
"This is unprecedented," Stachura said. "Comets are usually not viewed until they are right upon us."
Stachura said comets offer important clues to scientists trying to unlock the deepest mysteries of the universe.
"One of the most important things about comets is they are leftovers from the formation of the solar system. They were there at the beginning," he said.
But comets also are a focus of fascination among those who never owned a telescope, giving them an attachment to both the heavens and the Earth's own past. Hale-Bopp, for example, was last seen by ancient peoples 4,200 years ago.
"This is something that hasn't been seen since the pyramids were built, so there is a kind of tie to history," Stachura said.
Folklore has been a part of humankind's curiosity with comets - from those who believed Halley would prompt an earthly disaster in 1910 to some who subscribe to the theory that Hale-Bopp is ushering an alien invasion.
But Stachura said an overwhelming number of people simply enjoy looking up to the skies.
"They're rare vents and they are something completely out of the ordinary," Stachura said.
Last year, a program at Eastern Elementary School in Hagerstown drew nearly 700 people who wanted to see Hyakutake, Martin said. That ended early when parking lot lights unexpectedly turned on, making it impossible to see the comet.
He expects at least as big a crowd this time, and the lights won't be turned on.
"The phone's been ringing off the hook," Martin said.
TriState Astronomers and the Washington County Planetarium will conduct three public viewings of Comet Hale-Bopp, weather permitting, at dusk on the following dates:
- April 2 at Renfrew Park in Waynesboro, Pa.
- April 5 at Eastern Elementary School in Hagerstown.
- April 11-12 at Antietam National Battlefield Visitors Center.
Telescopes will be provided. For more information, contact planetarium resources teacher Rodney Martin at 766-2898.