Astronomers have detected water vapor in the atmosphere of a planet that orbits within the habitable zone of its star.
“This is the only planet we know of outside the solar system that [has] the correct temperature to support water, has an atmosphere, and has water in it, making this planet the best candidate for habitability we know of right now,” Angelos Tsiaras told reporters. Tsiaras is an astronomer at University College London (UCL) in the United Kingdom and the lead author of a new paper on the planet.
This is also the first time that water vapor has been detected in the atmosphere of an exoplanet that is not a gas giant.
Habitable, but Maybe Not Hospitable
K2-18b was discovered by way of the Kepler Space Telescope in 2015. A few months later an astrophysicist at the Université de Montréal in Canada who was not involved with this study, used the Hubble Space Telescope to observe the planet passing multiple times in front of its star at infrared wavelengths. This technique measures the chemical fingerprint of a planet’s atmosphere as starlight passes through it. Tsiaras and his team analyzed those data with their own software when Benneke’s data became publicly available.