Webb maps weather on distant planet which is so hot that it can melt iron

The James Webb Space Telescope has for the first time mapped the weather on a planet where daytime temperature soars up to 1,250 degrees Celcius and falls to 600 degrees Celcius during night.

Astronomers used the world’s most powerful observatory to find the presence of thick, high clouds covering the nightside, clear skies on the dayside, and equatorial winds upwards of 5,000 miles per hour mixing atmospheric gases around WASP-43 b.

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The planet is similar in size to Jupiter, made primarily of hydrogen and helium, but much hotter than any of the giant planets in our own solar system. It orbits a star, smaller and cooler than the Sun, at a distance which is 1/25th the distance between Mercury and the Sun in our own Solar System.

What has Webb found?

Webb found that the planet is tidally locked with its Sun, which means that one side is 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.

“With Hubble, we could see that there is water vapour on the dayside. Both Hubble and Spitzer suggested there might be clouds on the nightside. But we needed more precise measurements from Webb to really begin mapping the temperature, cloud cover, winds, and more detailed atmospheric composition all the way around the planet,” Taylor Bell, lead author of the study published in Nature Astronomy explained.

The planet completes an orbit around the Sun in just 19.5 hours.

The measurements from Webb’s observations revealed that the dayside has an average temperature is nearly 1,250 degrees Celsius, hot enough to forge iron, and the nightside is significantly cooler at 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 in the U.K.

Astronomers were also able to map water vapour (H2O) and methane (CH4) around the planet. “Webb has given us an opportunity to figure out exactly which molecules we’re seeing and put some limits on the abundances,” said Joanna Barstow, a co-author from the Open University in the UK.