Liquid gems may rain from the sky on this hot exoplanet

Every 30 hours, WASP-121b completes one orbit and is gradually locked out, just like the Moon with the Earth. This means that one side of the planet, besides the day, always faces the star. The other side lives perpetual night facing space.

Study co-author Tansu Dilan, a postdoctoral research fellow in astrophysics at MIT, said in a statement.

Now, astronomers have studied both sides of the planet to better understand the atmosphere and exotic weather using the Hubble Space Telescope.

severe water cycle

On Earth, water evaporates and its vapor condenses in clouds, then releases rain. In WASP-121b, water goes through a vicious circle.

Water atoms disintegrate due to the high temperatures that the planet experiences throughout the day. These atoms are carried to the night side by winds of more than 11,000 miles per hour (17,703 kilometers per hour). There, the molecules coalesce again to form water before being pushed to the side of the day again.

“These winds are much faster than our jet stream, and they can probably move clouds across the entire planet in about 20 hours,” Dylan said. He previously studied the planet using data from NASA’s Transiting Exoplanet Survey Satellite mission.

Temperature differences between the two sides of the planet also mean that the night side is cold enough to form metallic clouds of iron and corundum. Corundum is a mineral found in sapphires and sapphires.

Just like the water vapor circulating on WASP-121b, these mineral clouds may be pushed along with the day as the minerals vaporize into gases. But before the clouds leave the night, they can release rain made of liquid gems.

“With this observation, we really get a global meteorological view of exoplanets,” said study senior author Thomas Michal Evans, head of the research group at the Max Planck Institute for Astronomy in Germany.

“Although thousands of exoplanets have been discovered, we have only been able to study their atmospheres for a small part because of the challenging nature of the observations,” he said. “We are now moving beyond just taking isolated snapshots of specific regions of the exoplanet’s atmosphere, to study them as three-dimensional systems as they really are.”

Michal Evans led the study while he was a postdoctoral student at the Kavli Institute for Astrophysics and Space Research at MIT.

extraterrestrial weather

The results also reveal the huge temperature differences between day and night on the planet, which the team identified by tracking the water cycle on WASP-121b.

Throughout the day, temperatures start at 4,040 degrees Fahrenheit (2,227 degrees Celsius) in the deepest layer of the atmosphere and reach 5,840 degrees Fahrenheit (3227 degrees Celsius) in the upper layer. At night, things are cooler and reverse, with the warmest temperature reaching 2,780 degrees Fahrenheit (1,527 degrees Celsius) and dropping as low as 2,240 degrees Fahrenheit (1,227 degrees Celsius) in the upper atmosphere.

Astronomers will observe WASP-121b later this year using the James Webb Space Telescope.

Study co-author Joanna Barstow, a research fellow at The Open University in the UK, said in a statement.