Scientists have used NASA's James Webb Space Telescope to map the atmospheric weather conditions on the hot gas-giant exoplanet, WASP-43 b. The international team of researchers made precise measurements of the planet's temperature and analyzed its atmosphere, unveiling the presence of thick clouds covering the nightside, clear skies on the dayside, and winds of up to 5,000 miles per hour circulating around the equator.

WASP-43 b, classified as a "hot Jupiter" type of exoplanet, shares similarities with Jupiter in terms of size and composition, primarily consisting of hydrogen and helium. However, this exoplanet is much hotter than any giant planet within our solar system. Despite orbiting a smaller and cooler star, WASP-43 b is extremely close to its star, positioned at only 1.3 million miles away – less than 1/25th the distance between Mercury and the Sun.

Due to its tight orbit, WASP-43 b is tidally locked, with one side continuously illuminated and the other covered in permanent darkness. Interestingly, strong eastward winds transport heat from the dayside, creating a unique climate on the planet.

Previous observations from telescopes like NASA's Hubble and Spitzer revealed the presence of water vapor on the dayside and suggested the existence of clouds on the nightside. However, the scientists needed more precise measurements to map the temperature, cloud cover, winds, and atmospheric composition across the entire planet. This led them to utilize Webb's advanced capabilities to collect data over an entire orbit.

Webb's Mid-Infrared Instrument (MIRI) measured the planet's brightness every 10 seconds for over 24 hours, allowing researchers to calculate temperature variations across different sides of the planet. The observations indicated an average temperature of nearly 2,300 degrees Fahrenheit (1,250 degrees Celsius) on the scorching dayside, while the nightside was relatively cooler at 1,100 degrees Fahrenheit (600 degrees Celsius). The data also helped identify the "hotspot," the hottest point on the planet, which was found to be slightly offset from the position receiving the most stellar radiation.

The analysis further revealed that the nightside of WASP-43 b is likely covered in thick, high clouds, which prevent some infrared light from escaping into space. Despite the high temperature, the presence of these clouds makes the nightside appear dimmer and cooler than it would be without them.

In addition, the researchers expected to detect methane, a common carbon molecule, on the nightside. However, the data from Webb showed a remarkable absence of methane throughout the planet's atmosphere. This suggests that supersonic winds, reaching speeds of approximately 5,000 miles per hour, are rapidly circulating gases from the dayside to the nightside and back again. This turbulent mixing prevents chemical reactions that would otherwise produce detectable amounts of methane on the nightside.

The findings from the investigation of WASP-43 b highlight the remarkable capabilities of NASA's James Webb Space Telescope in measuring temperature variations and identifying atmospheric gases on exoplanets located trillions of miles away. The Webb Early Release Science programs have provided researchers with valuable and accessible data to study diverse cosmic phenomena.

As the world's premier space science observatory, the James Webb Space Telescope continues to unlock mysteries within our solar system while exploring distant worlds and unraveling the origins of our universe. Developed through an international partnership led by NASA, along with the ESA and the Canadian Space Agency, Webb is at the forefront of exoplanet science, helping scientists to gain a deeper understanding of the vast expanse beyond Earth.