We’d probably recognize life as we know it, however many light-years away it is, but what about life as we don’t know it?

NASA’s Nexus for Exoplanet System Science (NexSS) is bringing together leading astronomers, biologists and geologists to not only search for aliens, but define what a planet teeming with life could actually look like both physically and chemically — even if it looks nothing like Earth.

Exoplanets that are rocky and temperate like our own are scattered all over the Milky Way. There could be some that seem to have all the right biosignatures but are hostile to life. There could be some that could appear barren and hostile until we realize that there is hidden life on them that follows a different and much more unexpected set of rules that don’t necessarily include breathing oxygen or photosynthesizing certain wavelengths of light.

“What does a living planet look like?” asked NASA astrobiologist and microbiologist Mary Parenteau, who recently co-authored five review papers on the subject. “We have to be open to the possibility that life may arise in many contexts in a galaxy with so many diverse worlds—perhaps with purple-colored life instead of the familiar green-dominated life forms on Earth, for example. That’s why we are considering a broad range of biosignatures.”

Green indicates life on Earth. Could it mean death on other planets?

What a habitable exoplanet could look like. Credit: NASA

Parenteau and colleagues took an inventory of biosignatures and tried to figure out how they should be interpreted if they show up on alien worlds. They are also investigating which instruments would be optimal for detecting anything that could be life, because the looming cosmic question is how to be able to distinguish a living planet or moon.

Titan’s lakes of methane and ethane may be toxic to us, but there has been much speculation that there could be some sort of life-forms swimming in those extraterrestrial waters.

Telescopes will have to level up and zero in if we want to at least attempt finding an answer. Observatories such as the Giant Magellan Telescope, the Extremely Large Telescope and NASA’s James Webb Space Telescope—should it not experience another delay—could analyze the atmospheric makeup of some of those rocky planets out there. Since we won’t be walking around on any of these planets soon, we need to rely on a telescope’s ability to observe the light reflecting off them what kinds of gases are swirling in their atmospheres.

“We won’t have a ‘yes’ or ‘no’ answer to finding life elsewhere,” said NASA astrobiologist Shawn Domagal-Goldman. “What we will have is a high level of confidence that a planet appears alive for reasons that can only be explained by the presence of life.”

Meaning, what qualifies as life elsewhere in the vast expanse of space could be something even sci-fi movies never dreamed of.

(via NASA)