The James Webb Space Telescope has mapped the climate of a planet 280 light-years away.

In accordance with NASA in Spanishprecise measurements hot gas giant exoplanet WASP-43 b brightness in a wide spectrum of mid-infrared light in combination with 3D climate models and previous observations from other telescopes.suggest the presence of thick, high clouds covering the night side, clear skies on the day side, and equatorial winds of more than 8,000 kilometers per hour mixing atmospheric gases around the planet.

Research is just the latest demonstration of exoplanet science, now possible thanks to Webb’s exceptional abilities to measure temperature changes and detect atmospheric gases over trillions of kilometers.

Tidally locked “Hot Jupiter”

OSA-43 b is exoplanet of the “hot Jupiter” type: similar in size to Jupiter, composed mainly of hydrogen and heliumand much hotter than any of the giant planets in our solar system. Although its star is smaller and cooler than the Sun, WASP-43 b orbits at a distance of just 2.09 million kilometers.less than 1/25 of the distance between Mercury and the Sun.

With such a narrow orbit, planet locked by tidal mechanismWith one side is constantly lit and the other is in constant darkness. Although the night side never receives direct radiation from the star, strong easterly winds transfer heat from the day side.

Since its discovery in 2011, WASP-43 b has been observed by numerous telescopes, including NASA’s Hubble and Spitzer space telescopes, which are now decommissioned.

“Using Hubble, we could clearly see that there was water vapor on the day side. Both Hubble and Spitzer suggested that there might be clouds on the night side.“he explained Taylor Bell, a researcher at the Bay Area Institute for Environmental Studies and lead author of the study published in the journal Nature Astronomy. “But we needed Webb’s more precise measurements to begin to truly map temperatures, cloud cover, winds and more detailed atmospheric composition across the planet.”

Although WASP-43 b is too small, dim and close to its star to be seen directly with a telescope, its short orbital period is only 19.5 hours. making it ideal for phase curve spectroscopy, a technique that involves measuring small changes in the brightness of a star-planet system as the planet orbits the star.

Because the amount of mid-infrared light emitted by an object depends largely on its temperature, Webb’s brightness data can be used to calculate the planet’s temperature.

The team used MIRI (Webb Mid-Infrared Instrument) to measure light from the WASP-43 system every 10 seconds for more than 24 hours. “By observing the entire orbit, we were able to calculate the temperature of different sides of the planet as they rotated through the field of view.“Bell explained.”From this, we were able to build a rough map of temperatures across the entire planet.“

Measurements show the average dayside temperature to be nearly 2300ºF/1250ºC., hot enough to forge iron. Meanwhile, the night side is significantly cooler, with temperatures hovering around 1100°F/600°C. This data also helps determine the planet’s hottest point (the “hot spot”), which is slightly offset to the east from the point receiving the most stellar radiation, where the star is highest in the planet’s sky. This shift occurs due to supersonic windswhich move heated air east.

“The fact that we can display temperature in this way is a true testament to the sensitivity and stability of Webb’s method.“, said Michael Romanco-author from the University of Leicester in the UK.

To interpret the map, the team used complex 3D atmospheric models, similar to those used to understand Earth’s climate. The analysis shows that the night side is likely covered by a thick, high layer of clouds that prevents some of the infrared light from escaping into space. As a result, the night side, although very hot, appears darker and cooler than it would be if there were no clouds.

Lack of methane and strong wind

The broad spectrum of mid-infrared light captured by Webb also made it possible measure the amount of water vapor (H2O) and methane (CH4) around the planet. “Webb gave us the opportunity to figure out exactly what molecules we were observing and set some limits on their number.“, said Joanna Barstowco-author of the UK Open University.

Spectra show clear signs of water vapor on both the night and day sides of the planet, providing additional information about the thickness of the clouds and how high in the atmosphere they extend.

Surprisingly, the data also shows obvious lack of methane anywhere in the atmosphere. Although the day side is too hot for methane to exist (most of the carbon must be in the form of carbon monoxide), methane should be stable and detectable on the cooler night side.

“The fact that we don’t see methane tells us that WASP-43b’s wind speeds should reach about 8,000 kilometers per hour.“Barstow explained.”If winds move the gas from the day side to the night side and back again quickly enough, the expected chemical reactions will not have enough time to produce appreciable amounts of methane on the night side.“

The team believes that because of this wind-induced mixing, the chemical composition of the atmosphere is the same across the planet, which was not apparent from previous work by Hubble and Spitzer.