NASA’s JWST Detects Clouds of Melted Rock Covering the Night Side of Hot Exoplanet WASP-43b

Using the James Webb Space Telescope, scientists have mapped the weather on an exoplanet 283 light years from Earth. The hot gas giant, called WASP-43b, was found to have one side permanently facing its star and the other locked in eternal night.

Transiting Planet WASP-43b

WASP-43b is a gas giant extrasolar planet that orbits a young, low-mass K-type star in the constellation Sextans. Formerly known as Astrolábos, it has a mass 1.8 times that of Jupiter and a width around 0.9 times that of the gas giant.

The exoplanet is so close to its star, WASP-43, that it completes orbit in just 19 Earth hours. This proximity at about 1.3 million miles (2.1 million kilometers) makes WASP-43b tidally locked to its host star.

Because of this tidal locking, one side of Astrolábos permanently faces the star and experiences daytime. Since this region is constantly bombarded by radiation, its planetary temperatures soar to about 2,300 degrees Fahrenheit (1,250 degrees Celsius), hot enough to melt lead. Meanwhile, the other side, which permanently experiences nighttime, gains a temperature of 1,110 degrees Fahrenheit (600 degrees Celsius). This condition classifies WASP-43b as a "hot Jupiter" planet.

Astrolábos was discovered in 2011 when scientists saw that WASP-43 exhibited a dip in the light. This dip happened as the planet crossed between the Earth and the face of its host star. During the transit, experts also observed a variation in the infrared light emitted by WASP-43b in response to starlight.

Weather Mapping of a Distant Planet

In a recent study, the James Webb Space Telescope predicted the extreme wind speed, hot temperatures, and blankets of rock clouds for WASP-43b. Using the Mid-Infrared Instrument (MIRI), the JWST Transiting Exoplanet Early Release Science (JTEC-ERS) was able to classify the exoplanet's climate and the type of weather it experiences on its day and night sides.

According to Max Planck Institute for Astronomy (MPIA) Director Laura Kriedberg, their team observed a complex, bleak world that demonstrates how odd alien worlds outside the Solar System can be. As Kriedberg noted, WASP-43b is a reminder of the vast ranges of climates that can be experienced on exoplanets and the many ways in which our planet is unique.

The primary result of the JWST investigation relies mainly on the observed infrared light variation between the exoplanet's dayside and nightside. More particularly, the variations helped astronomers create a map showing the distribution of temperatures across the entire hot gas giant.

Finally, the research team discovered that the variation in temperature between the day and night side of Astrolábos is too significant to be observed in an atmosphere deprived of cloud cover. According to scientists, any possible clouds above WASP-43b could not be water-based like the one that envelops the Earth. They would not also be ammonia clouds like those enshrouding Jupiter. Since WASP-43b is too hot for water or ammonia-based atmosphere, the clouds in this strange world might be made of rock.

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