BBC SCIENCE FOCUS - Our search for extraterrestrial life might have just got a whole lot easier. Now, if aliens so much as modify a planet in their solar system to make it warmer, we would be able to tell.
That's thanks to a new study from The University of California, Riverside, which has identified the artificial greenhouse gases that would be obvious giveaways of a terraformed planet (one that has been artificially modified to be hospitable for life).
The gases described in the study – fluorinated versions of methane, ethane, and propane, along with gases made of nitrogen and fluorine or sulfur and fluorine – could be detectable using existing technology in the atmospheres of planets outside our own solar system. This means it's possible the James Webb Space Telescope could one day soon spot an alien civilization.
In large volumes, such gases would act as pollutants on Earth (further spurring climate change). Sulfur hexafluoride, for example, has 23,500 times the warming power of carbon dioxide – a small amount of this could heat a freezing planet to the stage of creating liquid water persistently.
However, there are potential reasons why extraterrestrials would use them on an exoplanet.
“[They’d] be good for a civilization that perhaps wanted to forestall an impending ice age or terraform an otherwise-uninhabitable planet in their system, as humans have proposed for Mars,” said Edward Schwieterman, an astrobiologist and lead author of the study.