What Would Alien Life Actually Look Like?

As we discover ever more planets orbiting other stars, and plan missions to potentially habitable moons of Saturn and Jupiter, will we find life – and if we do, will we even recognise it?

- Mićo Tatalović

Our Universe could turn out to be a pretty wild place. Recent astronomical discoveries suggest that billions of Earth-like planets are dotted throughout our Galaxy, which is just one of billions of galaxies in the Universe. “Our best estimates are that one in four stars have a planet that is the same size and the same temperature as the Earth. That’s very high,” says David Charbonneau, professor of astronomy at Harvard University, US.

And many scientists now think there is life on at least some – if not many – of those planets and their moons. One of them is Dr. Chris McKay, a planetary scientist at NASA’s Ames Research Center, who says that we can assume that life is widespread based on “two simple facts”.

First, the chemical elements of life, such as nitrogen, hydrogen, and oxygen, are widespread in the Universe, as are the two key compounds of life on Earth: liquid water and organic carbon. Second, we know that life was present on Earth very early in its history – soon after the planet was formed – which suggests that once the conditions are right, life springs up easily and quickly.

“If the origin of life is widespread, then complex life will be widespread,” says McKay. That means we might expect to find more than just single-celled microbes out there. “The best way to find out is to go look.”

Some scientists and entrepreneurs are already thinking about how to get to distant stars quickly. Yuri Milner, a Russian tech entrepreneur, came up with the Breakthrough Starshot project, which proposes that tiny chips could be attached to craft propelled through space by an intense Earth-based laser. If it works, this would cut the travel time to the closest star system, Alpha Centauri, from 100,000 to just 20 years. The first tests of early designs took place this May.