JWST Maps the Weather on a Hot Gas Giant 700 Light-Years Away

For the first time, astronomers have mapped the weather on a hot gas giant 690 light-years from Earth. WASP-94A b, a tidally locked planet, orbits close to one of the stars in a binary system. A team led by Sagnick Mukherjee, an astrophysicist at Johns Hopkins University, used the James Webb Space Telescope to study the planet's atmospheric conditions.

The fact that WASP-94A b is tidally locked means that its day- and night-side temperature differences are nonexistent, sparking questions about the planet's atmospheric dynamics. "We wanted to understand the atmospheres of such planets," Mukherjee says. "Are they static or dynamic?

Do they have winds? Do they have clouds?" The team's findings, published in a new Science study, reveal that WASP-94A b has a cloudy morning and clear evening skies. The planet itself is a behemoth, with a mass slightly below half of Jupiter's but a diameter over 70 percent wider.

This low-density composition means its atmosphere extends far into space, making it more accessible to observation. Mukherjee explains that astronomers typically study atmospheres like WASP-94A b's using transmission spectroscopy, analyzing the light spectrum filtering through the planet's atmosphere as it passes in front of its star. The discovery of WASP-94A b's unique weather pattern has significant implications for exoplanet chemistry.

The fact that scientists didn't know this about WASP-94A b before suggests that they may have gotten the chemistry of this and many other exoplanets surprisingly wrong. As Mukherjee's team continues to explore the atmospheric conditions on distant planets, they may uncover more surprises that challenge current understanding of exoplanet chemistry. The James Webb Space Telescope has opened a new window into the atmospheric conditions on distant planets, allowing scientists to study the weather on worlds like WASP-94A b in unprecedented detail.

With this powerful tool, astronomers can now probe the atmospheres of hot gas giants and uncover the secrets of their complex weather patterns.