Do Aliens Litter?

Jul 25, 2014 at 11:55 AM ET

Scientists have been studying the surfaces of other planets for decades, looking for life.

So far, they haven’t found much.

But some of the world’s top ET-chasers announced a new plan this week: Instead of scouring the planet surfaces for life, they’re going to begin looking for space litter. The idea is that if aliens exist (or ever existed), then they’d probably pollute the space around them—just like we do.

“People often refer to extraterrestrials as ‘little green men,’ but the ETs detectable by this method should not be labeled ‘green,’ since they are environmentally unfriendly,” says Avi Loeb, a science professor at Harvard and one of the researchers pursuing this bold new plan, in a classic dad joke.

Using a high-powered telescope, the scientists will begin looking for chemicals—particularly chlorofluorocarbons, which are destroying the ozone layer and come from things like aerosol cans—in the atmosphere around planets in our solar system. 

This isn’t the first time scientists have proposed creative methods to search for aliens. Researchers at the University of Edinburgh suggested in 2011 that aliens might have one day tried mining asteroids to look for resources. So if we analyze giant asteroids still hurtling through space, they argued, we might see their alien fingerprints.

Meanwhile, we’ll have to wait to find out the Martian version of crumpled gum wrappers and empty Doritos bags.