If the prototypical alien is the gruesome monster that a crew of highly unfortunate humans found in a remote space outpost in the film Aliens, with Sigourney Weaver, you might say our future seems bleak. The aliens in that film – actually a series that began with Alien in 1979 – are terrifying and bloodthirsty, salivating from their two sets of jaws, bent solely on turning human bodies into wombs from which baby aliens violently burst.

But come on, just how realistic – biologically speaking – is an alien whose blood is acidic enough to eat through several decks of a spaceship? Or what about the Martians in H.G. Wells's The War of the Worlds, hideous blobs with Gorgon-like tentacles descending from their quivering mouths, pipetting victims' blood into their own veins?

Or, for that matter, the blob in the Steve McQueen movie of the same name? There has been no shortage of alien depictions in literature, comic books and film.

But now scientists are putting some extra thought into the idea of aliens. They've come up with some interesting results.

An exhibition, set to open April 10 at the Montreal Science Centre, intends to add scientific rigour to a subject heretofore solely the domain of human imagination.

Using the expertise of a number of renowned scientists, the exhibition presents ideas on what aliens might look like, taking into consideration biology, astronomy, and the laws of physics and chemistry.

"It's fiction, yes, but it's science-based science fiction," says Louise Julie Bertrand, the head of exhibitions at the Centre. Such an exercise, she adds, will appeal to both kids and adults. "People are often attracted to the bizarre and intriguing and weird."

The stars of the exhibition are these alien forms envisioned by the scientists to fit the specific characteristics of two "planets," such as carbon content, the temperature, the type of atmosphere.

"It was a real attempt to come up with creatures, that, although fanciful, are plausible," says Michael Meyer, an astrobiologist and the lead scientist for NASA's Mars Exploration Program.

The exhibit opens with depictions that authors and filmmakers have dreamed up. A common theme is how aliens are viewed as the other, just as witches – and even Communists – have been.

"Through the ages, they have always been something we feared," Bertrand says. "Dragons, witches, aliens, this is a recurring (theme) through history. The stranger, the person different from us, this is who we'll focus our fears on."