Aliens could be spotted by their pollution
While parent stars transport by their exoplanets, a good amount of information about its structure and habitability from the light that is filtered through the atmosphere. Normal chemical trackers for life would contain water vapor and carbon dioxide, but the new James Webb Space Telescope (JWST) could possible pick up pollution from intelligent life. Avi Loeb of the Harvard-Smithsonian Center for Astrophysics (CfA) has led the research that would bring up new topics in the search for extraterrestrial intelligence (SETI). The Astrophysical Journal has accepted the paper for publication.”We consider industrial pollution as a sign of intelligent life, but perhaps civilizations more advanced than us, with their own SETI programs, will consider pollution as a sign of unintelligent life since it’s not smart to contaminate your own air,” lead author Henry Lin explained in a press release.
Chlorofluorocarbons (CFCs) were commonly used as refrigerants, solvents, and aerosol propellants, but now aren’t used since the Montreal Protocol of 1987 because of their ozone-depleting properties. Two types of CFCs could possibly be spotted by JWST, indicating the atmospheric concentrations of these pollutants are ten times more than on Earth. “People often refer to ETs as ‘little green men,’ but the ETs detectable by this method should not be labeled ‘green’ since they are environmentally unfriendly,” Loeb quipped.
The exoplanets will have to orbit white dwarf stars in order to detect the pollution. When a star dies and it’s not big enough to become a neutron star, then it becomes a dwarf star. The majority of the stars in the milky way are like this (97% to be exact). Though, before becoming a white dwarf, it becomes a red giant and swells up. Then it could very well consume the planet’s atmosphere. CFCs don’t get eliminated from the atmosphere at the same rate. Some pollutants are removed in about a decade, but some can lasts thousands of years on Earth. It is possible that a source is still there is a mix of pollutants are detected. “In that case, we could speculate that the aliens wised up and cleaned up their act. Or in a darker scenario, it would serve as a warning sign of the dangers of not being good stewards of our own planet,” says Loeb.
