How We Could Find Aliens By Looking For Their Pollution

How We Could Find Aliens By Looking For Their Pollution

Remember chlorofluorocarbons, aka CFCs? The big, bad ozone-depleting pollutant 1) sticks around for tens of thousands of years and 2) is almost entirely man-made. That means if extraterrestrial life are anything like us, according to astrophysicists at Harvard, CFCs could be a key to finding aliens.

First, a quick primer on how we could even detect pollution on faraway planets. In a few years, NASA will be launching its powerful, new James Webb Space Telescope (JWST), which will capture starlight filtering through atmospheres of exoplanets. By comparing the spectrum of light before and after it goes through an atmosphere, astrophysicists can figure out the gases that make it up.

Usually, when scientists are looking for signs of life, they're looking for oxygen, a highly reactive molecule that only exists in Earth's atmosphere because photosynthesising plants and bacteria keep replenishing it. (There was, in fact, a time in Earth's history when there was very little oxygen in the air.) But if we want to zero in on intelligent life — not just plants and bacteria — maybe we should look for industrial pollution.

A trio of astrophysicists at Harvard have calculated that the JWST could indeed detect CFCs on a planet orbiting a white dwarf. Gases like methane and nitrous oxide, which are also indicative of but not exclusive to human (or alien) activity, would also be detectable.

That's all assuming aliens would be as destructive toward their planet as we are. Perhaps the most fascinating and sobering detail of all is that because CFCs last for up to 100,000 years, we could be detecting alien civilizations and their polluting legacy long after they're gone. [ArXiv via New Scientist]

Picture: A super-Earth-size exoplanet. NASA Ames/JPL-Caltech

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    Ok so maybe we can find Aliens via CFCs. That's all fine and dandy, right? Maybe not, if there is another lifeform out the stupid enough to pollute its own planet then perhaps it is best left alone.

      We didn't know CFCs were do detrimental to the environment until it was show to be destroying the ozone layer. And CFCs have such amazing chemical properties that when any intelligent species discovers them they are bound to use them until they see their folly. Really the mark of a good species is their ability to rally around a cause and bring positive change. Like banning the use of CFCs after they find they are bad.

      As Nazgeek says, nobody really knew what the effects were at the time, but they were so good and the then-current understanding of the science supported their use. It's the same with pharmaceuticals - what seems awesome in the short term might have long-reaching consequences that don't turn up until later. Sometimes you just don't know about something until after the fact - hindsight is near flawless, foresight often isn't.

        I see what you guys mean. Ok, from now on any Aliens we find who pollute their planets while knowing the damage CFCs cause should also be considered a threat.

    Some future generation will be tutting at us and our silly and dangerous use of non-stick fry pans.

    Of course, this is also entirely counting on the presence of hydrocarbons which are then converted to fluorocarbons. Hydrocarbons can occur naturally (eg. Titan's atmosphere) but on earth the majority are created by the photosynthesis process. Who is to say than an inhabited alien planet has any such process, or is even Carbon based life to begin with?

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