In a landmark revelation announced December 25, 2023, scientists using the James Webb Space Telescope (JWST) have, for the first time, definitively detected carbon dioxide in the atmosphere of a rocky exoplanet.The exoplanet, WASP-39 b, is located 700 light-years away in the constellation Virgo and orbits a sun-like star.

While carbon dioxide has been previously identified in the atmospheres of gas giants, this marks the first time it has been confirmed in a rocky planet’s atmosphere. WASP-39 b is not habitable – it’s a hot gas giant with a temperature exceeding 900 degrees Celsius – but the detection demonstrates JWST’s unprecedented ability to characterize the atmospheres of rocky exoplanets, paving the way for the search for signs of life on perhaps habitable worlds.

The findings, published in Nature, were made possible by JWST’s Near-Infrared Spectrograph (NIRSpec). nirspec analyzes starlight filtered through the exoplanet’s atmosphere,revealing the chemical composition. The strong absorption signature of carbon dioxide at 4.3 microns was clearly identified in the data.

“As soon as the data appeared on my screen, the prominent carbon dioxide feature jumped out,” said Natalie Batalha, an astronomer at the University of California, Santa Cruz, and a member of the research team. “It was a special moment, crossing an vital threshold in exoplanet science.”

WASP-39 b was first discovered in 2019 by the WASP (Wide Angle Search for Planets) survey, a ground-based program that detects exoplanets by observing the slight dimming of a star as a planet passes in front of it (a transit). the planet is approximately the size of Saturn but has a much lower mass, making it less dense.

This discovery isn’t just about finding carbon dioxide; it’s about the implications for future exoplanet research.Carbon dioxide is a crucial molecule for understanding planetary formation and evolution. Its presence, or absence, can provide clues about a planet’s history and potential habitability. JWST’s ability to detect and measure carbon dioxide will be instrumental in the search for biosignatures – indicators of life – on smaller, rocky planets that more closely resemble earth.

Future observations with JWST are planned to target TRAPPIST-1 b,c,and d – rocky exoplanets orbiting an ultra-cool dwarf star approximately 40 light-years away.These planets are considered prime candidates in the search for extraterrestrial life. The team hopes to use the same techniques employed with WASP-39 b to analyze the atmospheres of these potentially habitable worlds.

The James Webb Space Telescope is an international collaboration between NASA, the European space Agency (ESA), and the Canadian Space Agency (CSA). It launched on December 25, 2021, and has been delivering groundbreaking scientific results since its commissioning in July 2022. The telescope is positioned at the Sun-Earth L2 Lagrange point, approximately 1.5 million kilometers (930,000 miles) from Earth.