JWST Provides a Weather Report from the Exoplanet Wasp-43 b

For centuries, humanity has been dreaming of a life among the stars. In some of those stories, humanity bands together and builds an almost magical technological future. In others, we scrape out an existence in space by the skin of our teeth. In SYFY’s The Ark, there’s a nice blend of both. Our descendants, about a hundred years from now, have succeeded in building a vast arc ship headed for Proxima centauri, but they were motivated by a quickly dying Earth. They’re leaving not because of a spirit of exploration, but because it is humanity’s last hope for survival.

If you’re planning to take a one-way trip several light-years across space in search of a new home, it might be helpful to know what to pack for. Using the James Webb Space Telescope (JWST), a team of astronomers recently managed to build a weather report for the exoplanet Wasp-43 b, 280 light-years from here. The results from this bit of cosmic meteorology were published in the journal Nature Astronomy.

For More on Exoplanets:
Water Vapor Found in the Atmosphere of Earth-Like Exoplanet GJ 9872d
Astronomers Find a Planet Half-Covered in Lava
Astronomers Find Clues for Alien Life on the Planet Most like Earth: Kepler-452b

The Weather Report for Exoplanet Wasp-43 b Is Hot, Sunny, and Super Windy

This artist’s concept shows what the hot gas-giant exoplanet WASP-43 b could look like Photo: NASA, ESA, CSA, Ralf Crawford (STScI)

JWST’s keen eye allowed astronomers to gather unprecedented detail of a distant exoplanet, opening up new avenues of planetary research. Wasp-43 b is a bizarre world by our standards, but its unusual characteristics make it an especially good target for study.

It orbits a relatively small star, about half the size and mass of the Sun, at a blisteringly close distance. Wasp-43 b is a tidally locked Hot Jupiter, about the same size of Jupiter, but orbiting only 1.3 million miles from its star. For comparison, Mercury sits about 43 million miles from the Sun, and the Earth is at a comfortable 93 million miles. Wasp-43 b orbits every 19.5 hours, and because it’s tidally locked, one side of the planet always faces the star.

On the dayside, the weather is always clear skies and sunny, on the other side of the planet it’s always dark, and astronomers wanted to know how that might impact the weather on Wasp-43 b. To find out, they pointed JWST at the system and took a measurement every 10 seconds for more than an Earth day. That allowed scientists to capture data throughout more than an entire orbit.

“By observing over an entire orbit, we were able to calculate the temperature of different sides of the planet as they rotate into view. From that, we could construct a rough map of temperature across the planet,” said the study’s lead author, Taylor Bell, in a statement.

JWST’s Mid-Infrared Instrument (MIRI) measured temperatures of about 2,300 degrees Fahrenheit (1,250 Celsius) on the dayside and a slightly comfier 1,100 degrees Fahrenheit (600 Celsius) on the nightside. Astronomers plugged that data into climate models similar to those used to model weather on Earth, to figure out what the skyscape looks like on Wasp-43 b.

This set of maps shows the temperature of the visible side of the hot gas-giant exoplanet WASP-43 b, as it orbits its star. Photo: NASA, ESA, CSA, Ralf Crawford (STScI)

Temperature maps of the exoplanet’s surface revealed a hot spot near where the planet faces its star. The hottest part of the surface is actually just off to the side, owing to strong winds which move hot gas away from the point of highest radiation. Models of the surface suggest the plant is covered in a layer of thick, high clouds on the nightside. Those clouds blocked some of the infrared light from escaping the planet, making it appear cooler than it actually is.

Researchers also expected to find methane on the nightside of Wasp-43 b. The dayside is too hot for methane to survive, but astronomers expected the cooler nightside to stockpile methane. Instead, they found no methane to speak of anywhere on the exoplanet. The leading explanation for the missing methane is breakneck winds with speeds in excess of 5,000 miles (8,000 kilometers) per hour. Those ferocious winds mix the atmosphere of Wasp-43 b, circulating gasses from the dayside to the nightside and back again fast enough that methane doesn’t have a chance to stick around.

The weather on Wasp-43 b doesn’t sound at all appealing, but the work that went into getting that weather report could inform future interstellar missions. Knowing what the forecast has in store could tell us whether to pack shorts and sunscreen or to pack it in and stay home.

Catch The Ark when it returns for Season 2, on Peacock.