Astronomers may have made a potential breakthrough in their search for habitable planets beyond our solar system with the recent detection of water vapor on a distant rocky planet. This marks the first time that an atmosphere has been directly detected around a rocky exoplanet, and if the water vapor came from the planet, it would suggest that it is possible for a rocky exoplanet with its harsh and challenging conditions to maintain or even re-establish an atmosphere.
The planet in question, GJ 486 b, is roughly 30% larger than Earth and has a mass three times greater than Earth. It orbits a red dwarf star in the Virgo constellation, 26 light-years away from Earth. Due to the planet being tidally locked, one side always faces the star, while the other is in perpetual darkness. This extreme and non-uniform environment has maintained scientists’ skepticism about the planet’s capacity for an atmosphere until the recent discovery of water vapor.
Grasping full confidence that GJ 486 b has an atmosphere isn’t a straightforward process. Its surface temperature, which is about 800 degrees Fahrenheit, is far too high for life to exist there. And it’s possible that the water vapor signal is originating from the host star GJ 486 itself, which is cooler than our sun. The concentration of water vapor within its starspots could mimic a planetary atmosphere, making the interpretation challenging.
While an atmosphere doesn’t equate to the presence of life, it does reveal an essential characteristic for habitability. The most common type of stars in the universe are red dwarfs, making rocky exoplanets orbiting them likelier to be discovered. However, red dwarfs release ultraviolet and X-ray radiation that can wipe out planetary atmospheres, leaving scientists questioning the ability for rocky planets to have and maintain an atmosphere and so habitable conditions.
The James Webb Space Telescope (JWST), which detected the water vapor on GJ 486 b, has gathered additional data since the initial discovery, using the Mid-Infrared Instrument (MIRI) and the Near-Infrared Imager and Slitless Spectrograph (NIRISS) to differentiate between water vapor released by the star and that originating from the planet’s atmosphere. While more observation and research are necessary, the detection of water vapor’s exciting potential offers new opportunities to explore the cosmos with unforeseeable benefits.
