A distant exoplanet could be surrounded by a steamy atmosphere, according to new measurements by the James Webb Space Telescope.
The planet, GJ 1214b, is a mini-Neptune – the most common type of planet in the Galaxy – in a close orbit around a red dwarf star, taking just 1.6 days to orbit.
The planet is shrouded in a cloud or haze layer that blocks most observations, but a team led by Eliza Kempton at the University of Maryland compensated for this by watching the planet for a complete orbit.
This revealed that the day side was 279˚C, while the night was just 165˚C – a disparity that is only possible if the atmosphere contains heavy molecules, such as water.
"We think we detect water vapour, but it’s challenging because water vapour absorption overlaps with methane absorption," says Kempton.
"We can’t say 100% that we detected water vapour and not methane. However, we see this evidence on both hemispheres of the planet, which heightens our confidence that there really is water there."
JWST and exoplanet science
For more on what the Webb Telescope can do in terms of observing planets beyond our Solar System, watch our video interview with astrophysicist Dr Hannah Wakeford from the University of Bristol
