Science 3 min read

Earth's 'Fingerprint' Could Help Find Habitable Exoplanets

Image courtesy of Shutterstuck

Image courtesy of Shutterstuck

We might never stumble on alien life — intelligent or otherwise — but we’d likely find habitable exoplanets before finding ETs.

Finding extraterrestrial life is like looking for a needle in a cosmic haystack!

As to why we try to find other inhabitable planets outside our solar system, this is a question that leads to other questions, answerable by:

How long can Earth survive our systematic environmental onslaught? How long can we survive in this ailing planet?

If we want to bring existential ruminations into the discussion, we have to look for habitable exoplanets. That’s because finding such worlds would be the most significant discovery ever about “life” as a concept in the Universe.

We know that wherever there could be life, it’s likely teeming life!

Certain terrestrial lifeforms, like tardigrades and other extremophiles, have been living on Earth’s harshest habitats, demonstrating their capability to survive even in outer space.

Our entire understanding about life and planet habitability comes from our experience as carbon-based intelligent life on Earth, the only planet supporting life that we know of.

Read More: Biosignature and the Search for Extraterrestrial Life

The Atmospheric Fingerprint of Habitable Exoplanets

Earth analogs, like rocky planets or exomoons, seem like potential candidates for being habitable and capable of sustaining life development.

Maybe, the low-hanging fruit approach is our best shot at finding potentially habitable exoplanets. That is, by taking a cue from Earth, which is the only life-hosting planet we know of in the whole Universe to date.

A team of two astronomers from McGill University in Montreal, Canada, have identified what they call a “fingerprint” for Earth, which they say could be used as a model to detect habitable exoplanets.

Evelyn Macdonald, McGill Physics student, and her supervisor Prof. Nicolas Cowan used over a decade of observational data of Earth’s atmosphere taken by the satellite SCISAT. Using the SCISAT data, they created a transit spectrum of Earth, a fingerprint for Earth’s atmosphere in infrared light.

This transit spectrum reveals the presence of key molecules that could signal the habitability of extra-solar worlds. One potential “biosignature” is the simultaneous presence of ozone and methane compounds in the atmosphere, which suggests an organic source. Prof. Cowan said:

“A handful of researchers have tried to simulate Earth’s transit spectrum, but this is the first empirical infrared transit spectrum of Earth. This is what alien astronomers would see if they observed a transit of Earth.”

Launched in 2003, SCISAT was developed by the Canadian Space Agency to monitor Earth’s ozone layer and other atmospheric gasses. Now, the satellite is helping in the quest for habitable planets in outer space.

Water vapor, methane, and ozone together with oxygen, carbon dioxide, and other biosignatures could mean a planet is habitable, or maybe that it is or was inhabited.

With the aid of this proposed atmospheric fingerprint-based approach, astronomers and astrobiologists can determine what kind of signs to look for in their search for Earth-like habitable exoplanets.

Read More: Why Extraterrestrial life in Outer Space Probably Exists on Eyeball Exo-Planets

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Zayan Guedim

Trilingual poet, investigative journalist, and novelist. Zed loves tackling the big existential questions and all-things quantum.

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