NASA has achieved the first clear detection of carbon dioxide in the atmosphere of a planet outside of our solar system using the ultra-powerful James Webb Space Telescope, the agency announced on Thursday.
The gas—important for life on our planet—was discovered in the atmosphere of exoplanet WASP 39-b, which is a hot gas giant about the size of Saturn that orbits a Sun-like star 700 light-years away from Earth. WASP 39-b is a transiting world, which means we can observe it when it passes in front of starlight that filters through its atmosphere. Gases absorb light differently, and so the super-sensitive JWST was able to pick out the telltale signs of carbon dioxide.
Hot gas giants like WASP 39-b don’t have well-defined surfaces, and so they aren't ideal for hosting life compared to rocky worlds similar to Earth. Its detection on that world tells us more about how it formed than what might live there. But the landmark CO2 detection does pave the way for analyzing alien worlds that might be habitable. After all, one of the main goals of the JWST program is to answer the question of if we're alone in the universe.
“Detecting such a clear signal of carbon dioxide on WASP 39-b bodes well for the detection of atmospheres on smaller, terrestrial-sized planets,” team lead Natalie Batalha of the University of California at Santa Cruz said in a statement.
Carbon dioxide on Earth is a heat-trapping gas that can be thrown into our atmosphere via abiotic processes like a volcanic eruption, or by living things that produce it naturally. It can also be produced through human activity like burning fossil fuels; it's a driver of climate change, and humans have increased the amount of the gas in our own atmosphere by a staggering figure. As pointed out by science publication New Scientist, researchers have theorized that carbon dioxide—in combination with other gases like methane—could be a valuable "biosignature" that points toward the existence of life on another world.
“Down the road, it may be an interesting biosignature when found in combination with other molecules like methane,” Jessie Christiansen from the NASA Exoplanet Science Institute told the outlet.
JWST was launched into space in December of last year, and the telescope's dazzling first images were revealed just last month. The telescope is really just warming up, and we have years of mind-blowing discoveries to look forward to.