The world’s most powerful telescope has made its first observations of a planet beyond our solar system, heralding a new era of astronomy in which distant worlds can be scanned for signs of life.
The observations, from NASA’s James Webb Space Telescope, provide new insights into the formation of the planet, a hot gas giant called Wasp-39b located 700 light-years away in the constellation Virgo. They also provide the first clear evidence of carbon dioxide in the atmosphere of a planet orbiting a distant star.
“We want to know how unique we are and what the chances are of life elsewhere in the universe,” said Dr Vivien Parmentier, associate professor of physics at the University of Oxford and a member of the collaboration behind the work “CO2 detection is typically one of the things we’ll be looking at. This shows that we have the capability, which is very exciting for all of us.”
A central goal of James Webb is to analyze the atmospheres of distant planets and search for biosignature gases that may indicate the presence of life on the planet below.
Wasp-39b itself is not seen as a promising candidate for life. The large gas planet is about 1.3 times the size of Jupiter, with an average temperature of about 900ºC. It is so close to its host star, about one-eighth the distance between the sun and Mercury, that it takes only about four Earth days to make a complete circuit.
Its proximity to the star means it is likely to be tidally locked, with one side constantly facing its star and the other side shrouded in unending darkness.
The planet was discovered in 2011, after astronomers noticed a subtle, periodic dimming of its host star’s light, caused by the planet passing in front of it. The latest work goes further by measuring the starlight that is filtering through the planet’s atmosphere. Because different gases absorb different wavelengths of light, analyzing the rainbow of starlight can tell exactly which gases are present.
Previous results from the Hubble and Spitzer telescopes had hinted at the presence of carbon dioxide, but the latest observations, to be published in the journal Nature, provide the first conclusive evidence.
Wasp-39b’s large size and cloudless atmosphere made it an ideal first target. Astronomers now plan to apply the same techniques to analyze the atmospheres of smaller, rocky planets thought to be potentially habitable, such as those in the Trappist-1 star system. They will look for Earth-like atmospheres dominated by nitrogen, carbon dioxide and water vapor and a global gas balance that hints at a contribution from biological processes.
“We’re looking for a combination of gases that we can’t easily explain with our understanding of the chemistry that could indicate that something is producing it,” said Dr Jo Barstow, an astronomer at the Open University and a member of the collaboration JWST. the paper
Sign up for Global Dispatch
Get a different view of the world with a roundup of the best news, features and images, curated by our global development team
Privacy Notice: Newsletters may contain information about charities, online advertisements and content funded by third parties. For more information see our Privacy Policy. We use Google reCaptcha to protect our website and Google’s Privacy Policy and Terms of Service apply.
Observing planetary atmospheres will also help astronomers distinguish between small, rocky planets that are more Earth-like and those closer to Venus, which is sometimes known as Earth’s evil twin because of its temperature surface temperature of 470 °C and its dense and toxic atmosphere.
“It was probably a bit of luck of the draw that Venus ended up so inhospitable and Earth ended up alive,” Barstow said. “It could have been a very small turning point that took them in such different directions.”