NASA scientists have announced that they’ve detected carbon dioxide on a planet 63 light-years from Earth. Earlier research on this planet, which is called HD 189733b, discovered molecules of water vapor and methane gas. The new find is another technical triumph, part of a growing effort to measure the chemical makeup of faraway worlds.
Astronomers probe the composition of space objects with spectrometers. These devices split the light shining from or reflecting off the object into its spectrum, or component colors. These colors bear fingerprints of the elements that make up the object. Astronomers cannot directly see HD 189733b because it is too faint and “blinded” by the light of its host star. So the team, which was led by Mark Swain, a research scientist at NASA's Jet Propulsion Laboratory in Pasadena, California, employed a visual trick to capture its light spectrum. They first scanned the light of the planet and its host star together using a spectrometer on the Hubble Space Telescope. They then scanned the star alone when the orbiting planet was hidden from view behind it. The difference between the two scans revealed evidence of carbon dioxide.
The find does not indicate that living things are producing carbon dioxide on HD 189733b. The planet orbits very close to its host star and thus is too hot to support life. Still, these chemical-tracing techniques may eventually find that life does exist outside of our Solar System.