The reason for the demand is the long-awaited return of Halley's Comet in 1986. The celebrated comet last swept the earth in 1910 and will not return again until 2061.

So Sun Line Cruises has added three new "cruising for comets" programs aboard its intimate 280-passenger Stella Oceanis. The ship will be positioned to coincide with what are expected to be the best views of the comet, from the Caribbean to Tangier, from the West Indies to South America, from West Africa to Europe.

Shipboard programs will be geared to the comet with many of the world's most respected authorities lecturing on the history and science of comets.

Other shipboard topics will range from how to photograph the comet to lectures on the constellations, stars and deep sky objects. Ohio astronomer Ted Pedas will lead many of the talks on the top deck late at night under the stars. Pre-sunrise talks — each day before sunrise the comet will appear higher and higher — are also on the horizon.

“The disco and casino do very little business on astronomy-oriented cruises because everyone spends most of their time star-gazing on deck,” says Pedas, a pioneer of the specialty cruise theme. He got the idea when he and his ex-school teacher sister-partner Marcy Sigler drove to Canada in 1963 to watch an eclipse only to have clouds block their view. They also tried to run a rock festival around an eclipse in 1970 in Eclipse, Va., but that ran into more clouds and red tape.

“We figured if we were at sea on an organized cruise, we wouldn't have any red tape and we could keep moving, following the stars” Pedas says — and thus a star was born as far as astronomical cruises were concerned.

Halley's Comet is named for 18th century English astronomer Edmond Halley, who first computed its orbit. It was regarded as a sign of imminent catastrophe at first — throughout history it has been connected to great events: cataclysms, wars, pestilence, famine, victories, the death of kings — and the fear has lingered. Indeed, when Halley's Comet last appeared in 1910, many feared its tail included gas that would destroy the world.

The comet has been described as a "vagabond chunk of dirt and ice" that streams like a pennant as it traverses the Milky Way about every 76 years. Nobody can explain why it is on that schedule, but records of its sighting date back nearly 22 centuries. It was sighted after the first Punic War ended, at Caesar's death, at Christ's resurrection, at the defeat of Attila, at the victorious progression of William the Conqueror and on and on throughout history.

It is visible to the naked eye, a ghostly tail of gas and dust that stretches tens of millions of miles across the heavens, one of the most spectacular yet predictable heavenly light shows. Indeed, the term comet comes from an ancient Greek word meaning long-haired, a reference to the fact that it appears cigar-shaped with its particles forming what look like a bushy mane and a long tail.

The first new Halley's Comet cruise leaves from San Juan March 28, 1986. It sails through the Caribbean on an 11-day itinerary that winds up in Belem, Brazil, at the mouth of the Amazon, described as “the new frontier for cruise ships.” An 18-day transatlantic cruise, from $2,335, begins in Belem March 28 and winds up in Palma de Mallorca on April 24.