Few events in the sweep of human history will be as significant and as far-reaching as contact with intelligent life in outer space, and now is the time for us to begin to prepare for the social and physiological impact, says Allen Tough, a retired education professor from the University of Toronto and an expert in future studies.

Scientists and the public have, in recent years, come to realize there is the distinct possibility that life on other planets exists, says Mr. Tough, and the effect of contact on human civilization will be profound.

"We must keep in mind that some of the intelligent life in our galaxy may be deeply alien to us. Their thinking patterns, knowledge, emotions, bodies, perception and communication may be even stranger than our strangest science-fiction images," he writes.

"Some intelligent beings in our universe could turn out to be silicon-based entities or supercomputers."

Douglas Vakoch, a psychologist with the Search for Extra Terrestrial Intelligence Institute in Mountainview, California, agrees. The organization, which has affiliates all over the world, is currently monitoring radio signals in anticipation of any signals from life in outer space.

It is Mr. Vakoch's job to research what the possible social impact will be on Earth.

"I think it is important to focus on this now, because it would happen so quickly and in such a short period of time it is better we prepare for a range of scenarios before the event occurs," he says.

Mr. Vakoch says two of the things that have to be considered when Earth receives a message are whether to respond right away, and what to say in return. One thing SETI has agreed on is that if a message from outer space is discovered, once it is confirmed by scientists from outside of the organization to authenticate the source, the message will be made known to the public right away.

"Any message that is sent isn't being sent to one person or one organization, but to the whole planet, so everyone should be aware of that."

Mr. Vakoch says that, if contact is made, not only would we learn a lot about the aliens, but also about ourselves, and we would begin to develop an Earthly identity.

"Some are afraid we won't feel unique any more, but I think the opposite will happen and we will realize how unique and special we really are," he said.

Ken Norwich, a professor of physiology at the University of Toronto who has done research into the potential sensory systems of life forms from other planets, isn't as optimistic about contact from outer space any time soon.

"There is the possibility that we may never find it, even if it is out there," he says. "Making contact isn't as simple as sending out a signal and getting a message back."

The subject of UFOs and outer space have become a preoccupation of the 20th century, he says, and it is partially fueled by the turn of the millennium.

"If we had lived 500 years ago, we would expect to see dragons or whatever was current, and right now we are obsessed with UFOs," he says.

"There is also certain magical attachment to the turn of the millennium, and we expect something special to happen at that time -- so why not it be someone from outer space?"

This isn't to say that we should stop looking, however, says Mr. Norwich.

"Science fiction writer Jules Verne talked about submarines long before we had them, so why not talk about this?" he asks.

"It's like the saying goes: 'If you ain't got a dream, how can that dream come true?'"

Meanwhile, Mr. Tough says it is important to consider what will happen to humans as a civilization in the event of contact with another species.

If the event is negative, it could possibly mean the extinction of humanity. However, he says this is very unlikely.

"What would probably happen is that any hostile society would wipe themselves out before they became highly advanced enough to travel to other planets," he said in an interview from his home in Toronto.

On the positive side, aliens could provide practical information that could help human civilization survive. They could also provide answers to some major questions about life and the universe -- because the chances are the extra-terrestrials would be much older than us, as our planet is relatively young in comparison to many of the stars that are in the universe.

"We might gain new insights, understanding and knowledge about major questions that go far beyond ordinary, practical, day-to-day matters," he writes.

"Topics in a message could include astrophysics, the origin and evolution of the universe, religious questions and the meaning of life."

Unlike the movies, in which space crafts land on Earth, Mr. Tough says he believes contact will probably made by way of a small probe, possibly the size of a basketball or smaller.

"It could be something that would be lurking around, monitoring our telecommunications in order to get to know us or our language."

Mr. Tough isn't alone in his beliefs. According to a Maclean's magazine poll last year, 42 per cent of Canadians expect an extraterrestrial civilization to be discovered within the next 50 years, and 17 per cent think the aliens will look like humans.

Although she doesn't believe extraterrestrials have a special interests in visiting earth, Canadian astronaut Julie Payette told radio listeners in Quebec in July that it is presumptuous for us to believe we are the only intelligent species in the universe.

There is no lack of alleged UFO sightings in Canada. According to a recent survey by a "Ufology" research group in Manitoba, there were 194 reports of UFO sightings in 1998, the majority of them in British Columbia and Ontario.

Some of the sighting descriptions in the study included a truck driver in Kelowna, B.C., who observed n big, silent, black triangular object moving slowly over the highway, and three people who witnessed a V-shaped object that flew over a house in Bancroft, Ont.