Extreme weather on the exoplanet Hot Jupiter is mapped by astronomers using the Webb space telescope

An international team of scientists has mapped the weather on a Hot Jupiter, or a gas giant in a close orbit around its host star, by using the James Webb Space Telescope’s capacity to detect atmospheric gasses and temperature fluctuations in far-off exoplanets. WASP-43 b is a well-studied exoplanet that was first identified in 2011 and is about 280 lightyears from Earth. Hubble and the now-retired Spitzer satellite observatory have both previously seen this planet.

WASP-43 b, like other Hot Jupiters, is tidally locked, meaning that its day side is always facing the host star and its night side is always in the dark, divided by an endless terminator line of twilight. High velocity winds whizz around the globe due to the huge temperature difference between the day and night sides, resulting in weather phenomena unparalleled in any other part of the Solar System.

In order to identify the presence of a thick layer of high altitude clouds covering the nightside of WASP-43 b, with clear skies on the dayside, and winds exceeding 8,000 kilometers per hour in the equatorial regions, the researchers combined the new observations by Webb with 3D climate models based on previous observations. Nighttime temperatures are 600°C, which is colder than daytime temperatures of 1,250°C, which is almost hot enough to forge iron.

The atmospheric concentrations of methane and water on WASP-43 b were also measured using Webb’s observations. Water vapor is evident on both the dayside and the nightside. In addition, the data showed a deficiency of methane, indicating that the planet is just too hot for methane to be stable. The results are detailed in an article that was published in Nature Astronomy.

“This planet is what we call a hot Jupiter, because it orbits so close to its host star—less than a quarter of the distance between Mercury and the Sun—that it is significantly hotter than any of the gas giants in our own Solar System,” explains Anjali Piette, one of the study’s authors. The formation or migration of these planets to such close-in locations, as well as the ways in which their host stars shape their atmospheres, are topics of great interest to astronomers.

Laura Kreidberg, director of the Max Planck Institute for Astronomy (MPIA) in Heidelberg, Germany, has spent ten years researching WASP-43 b. According to Kreidberg, WASP-43b has been revealed in previously unheard-of detail thanks to JWST’s increased observation capacity. We see a complicated, hostile environment with violent winds, drastic temperature swings, and sporadic clouds that are probably composed of small rock fragments. The wide variety of climates that may exist on exoplanets and the several ways in which Earth is unique are brought to light by WASP-43b.