Researchers use MIRI to map weather on exoplanet 280 light years from Earth
01 May 2024



NASA and ESA have released details of new research using JWST to study the weather on hot gas-giant WASP-43 b.

Artist's impression of what exoplanet WASP-43 b​ might look like.

Artist's impression of WASP-43 b​

NASA, ESA, CSA, Ralf Crawford (STScI)

WASP-43 b is a “hot Jupiter" type exoplanet made primarily of hydrogen and helium. It obits a star at a distance of just 1.3 million miles (to give you some perspective Earth is just over 150 million miles from our Sun).

As stated in NASA and ESA's press release:

With such a tight orbit, the planet is tidally locked, with one side continuously illuminated and the other in permanent darkness. Although the nightside never receives any direct radiation from the star, strong eastward winds transport heat around from the dayside.

The team used Webb's MIRI (the Mid InfraRed Instrument) to measure light from the WASP-43 system every 10 seconds for more than 24 hours. “By observing over an entire orbit, we were able to calculate the temperature of different sides of the planet as they rotate into view," explained Taylor Bell [researcher from the Bay Area Environmental Research Institute and lead author of a study published in Nature Astronomy]. “From that, we could construct a rough map of temperature across the planet."

The measurements show that the dayside has an average temperature of nearly 2,300 degrees Fahrenheit (1,250 degrees Celsius) – hot enough to forge iron. Meanwhile, the nightside is significantly cooler at 1,100 degrees Fahrenheit (600 degrees Celsius).

“The fact that we can map temperature in this way is a real testament to Webb's sensitivity and stability," said Michael Roman, a co-author from the University of Leicester. 

​​The research provided more data on the atmospheric conditions on WASP-43 b.

“The fact that we don't see methane tells us that WASP-43 b must have wind speeds reaching something like 5,000 miles per hour," explained Joanna Barstow [a co-author from the Open University]. “If winds move gas around from the dayside to the nightside and back again fast enough, there isn't enough time for the expected chemical reactions to produce detectable amounts of methane on the nightside."

Read the full story at