In the Milky Way alone, there are 60 billion planets that could be home to alien life -- and that life could take any fantastic form, ranging from massive icebound microbial networks, to bioluminescent underwater predators, to highly advanced robot races.

At least those are some of the imaginings in "Aliens: The Definitive Guide," a two-hour special airing Sunday at 8 p.m. ET on Discovery Canada as part of Aliens Week.

The project's goal is to establish a benchmark on what extraterrestrial life could look like, where it is most likely to exist and whether it will find us before we find it.

And, of course, there’s the questions of whether alien life even exists in the first place.

"Some scientists say that perhaps we are the only life forms in the universe," says Dr. Michio Kaku, a theoretical physicist at the City University of New York, and one of the experts cited in "Aliens."

"Give me a break. I mean how many stars are there out there in the universe anyway? The Hubble space telescope can see about 100 billion galaxies, that’s the visible universe. Each galaxy consists of 100 billion stars... There definitely are aliens in outer space, they're out there."

Directed by Britain's Mike Davis, "Aliens" was a co-production between Montreal's Handel Productions and the U.K.'s Arrow Media -- with special effects by Montreal's Mokko Studio.

Davis, who comes from a visual effects background working on computer graphics-heavy projects, said it seemed like the right time to embark on such a project.

He said new technology such as the Kepler space telescope is allowing astronomers to discover more new planets than ever before. And some of them lie in the so-called "goldilocks" zone, where life could theoretically exist since the conditions are “just right.”

As a result, Davis said, the possibility of alien “first contact” appears more likely than ever.

"It felt like now was a really good time for our audience to find out about lots of exciting areas of science -- very, very credible science where there are possible breakthroughs taking place when it comes to the discovery of life off the Earth," Davis said in an interview from London.

"We're chalking up lots of planets: we know how big they are, how dense they are, we can make certain assessments about what the chemistry of their atmospheres are like. We're nominating Earth-like planets all the time that seem to have conditions that might be suitable for life."

The project features some of the world's leading experts in their fields, from theoretical physicists to planetary scientists and astrobiologists -- all of whom share their visions of the many possible forms alien life could take.

Cutting-edge science is the "anchor," Davis said, which allowed the team to delve into the science fiction side, using CG graphics to explore what alien worlds and extra-terrestrials themselves would look like, and how humans would interact with them.

"There's a backbone of real science but each of those real science areas is a springboard to lovely science fiction, like the visuals and brilliant ideas we're familiar with in movies and TV shows and so on. But it’s always anchored in the real world scientific discoveries we're making now."

Dr. Lewis Dartnell, an astrobiologist at University College London, outlines in the film a number of fantastic evolutionary directions that life could take on other planets.

  • Water world: On a planet covered in massive oceans hundreds of kilometres deep, aquatic life forms would have to evolve to survive in the dark depths far from the sun's light. From observing species that exist in the deepest parts of Earth's oceans, we can form an idea of how they would look and live -- likely hunting in packs, using bioluminescence to co-ordinate attacks and avoiding the monsters of the deep that would, in turn, prey on them.
  • Ice world: On a planet made of ice, far from the star it orbits, it's possible that life could exist -- just not in the alien form typically portrayed in films or books. In that case, life trapped deep in the ice would likely take the form of bacteria that has developed a new way of absorbing energy by creating "long fibres of bacteria, all joined together to create vast networks of biological circuitry to extract energy from a magnetic field."
  • Heavy gravity world: On a planet several times the size of Earth, it's possible that flying creatures would have evolved to take advantage of the heavier gravity. Able to generate much more flying force in the thicker, denser atmosphere, it’s possible they would be much larger and more powerful and aggressive than Earth's birds.
  • Earth-like environment: In a world with a similar environment to Earth, it would be a mistake to assume life would have evolved into similar forms. Dartnell envisions massive octopi with exoskeletons developed to walk on land after they emerged from an aqueous environment into the heavy gravity of the surface. The "biggest, baddest extra-terrestrials" could live on an Earth-like planet where evolution has taken a very different turn, he said.

Other experts in the film envision species that have evolved far beyond humans – and are able to control their own evolutionary process and create computers and robots to do their work for them. Still other scientists are attempting to create life forms on Earth using elements known to be present on other planets.

The film also features groups of experts who are searching the cosmos for incoming messages sent from other extra-terrestrials, similar to the film “Contact.”

But Davis said he was astounded to learn there are also entire groups of people sending sophisticated messages out into space in hopes that somewhere out there, aliens are scanning their own skies for incoming signals.

Others, he said, are working to develop telescopes that could actually see far enough into space to detect evidence of life on far-off planets, or searching for Dyson spheres -- hypothetical structures built around stars to harness their energy and support alien civilizations.

Davis said these advances excite him, but also leads to a frustrating reality.

"It seems like we very soon will identify a planet that is very Earth-like. It's possible we will be able to analyze the chemistry of that atmosphere from the light it is throwing back at us, and it might be we have telescopes powerful enough even to be able to see lights on that planet or evidence of industrial activity. But we're just not going to be able to develop technology that allows us to get there," Davis said.

That realization was one of the "slightly downer" moments of the project, he said.

Unless Star Trek-like warp drives can be developed (yes, scientists are working on them), which allow travel up to and beyond the speed of light, those worlds will remain unreachable for at least a century.

"At the current rate, it's going to take us 73,000 years to reach the nearest planet that might be habitable that surrounds a star -- we would need to reduce that significantly," he said.

Of course, he said, none of that will really matter if the aliens reach us first.