Astronomers using NASA's James Webb Space Telescope have detected the first atmosphere on the rocky exoplanet LHS 1140b [1].
This discovery marks a critical milestone in the search for extraterrestrial life. Finding an atmosphere on a rocky, temperate world provides the first concrete evidence that Earth-like conditions may exist elsewhere in the universe [2].
LHS 1140b orbits the red-dwarf star LHS 1140, located approximately 49 light-years from Earth in the constellation Cetus [1]. The planet is roughly 1.4 times the radius of Earth [3]. Because it orbits its star at a specific distance, it sits within the habitable zone, the region where temperatures could allow liquid water to exist on a planet's surface [1].
An international team of researchers reported the findings this month [2]. The detection and characterization of this atmosphere distinguish LHS 1140b from the approximately 6,000 exoplanets discovered to date [4]. While previous observations have identified atmospheres on gas giants or planets orbiting dead stars, this is the first such atmosphere found on a rocky world within a habitable zone [1].
Researchers used the advanced infrared capabilities of the Webb telescope to analyze the light passing through the planet's periphery. This method allowed the team to identify the chemical signatures of the atmosphere [2]. The presence of a stable atmosphere suggests the planet has resisted the intense radiation often emitted by red-dwarf stars, which frequently strip away the gaseous envelopes of nearby planets [2].
The team said the discovery advances the scientific ability to identify potentially habitable worlds. By studying the composition of the atmosphere, astronomers hope to determine if the planet contains gases that could support biological life [2].
“the first atmosphere found on an Earth-like world within its star’s habitable zone”
The detection of an atmosphere on LHS 1140b shifts the focus of exoplanetary research from merely finding 'Earth-sized' planets to identifying 'Earth-like' environments. Because red-dwarfs are the most common stars in the galaxy, proving that a rocky planet orbiting one can retain an atmosphere significantly increases the statistical likelihood that habitable worlds are common throughout the Milky Way.
