The James Webb Space Telescope (JWST) has revealed a distant alien planet to be cloudy with a chance of active chemistry. WASP-39 b, aka “Bocaprins,” orbits a star slightly smaller than our Sun about 700 light-years distant in the constellation of Virgo in our Milky Way galaxy.
A so-called “hot Saturn” planet, Bocaprins was first examined in summer when JWST began its science observations, but it’s now revealed the planet’s full chemical profile—and made some unique discoveries.
Splitting the planet’s faint light into a spectrum scientists can see the telltale signs of atoms, molecules and active chemistry involving water, sulphur dioxide, carbon monoxide, sodium and potassium. It’s thought to have a fuzzy orange-blue atmosphere with cloud bands below.
Both Webb and the Hubble Space Telescope have previously revealed one-off ingredients of this hot planet’s atmosphere, but this “full menu” is a first. The data also revealed that the planet’s clouds could be broken up rather than a uniform blanket.
This is great news for a scientific community desperate to explore smaller, rockier and more Earth-like planets such as those in the TRAPPIST-1 system.
“This is the first time we have seen concrete evidence of photochemistry — chemical reactions initiated by energetic stellar light — on exoplanets,” said Shang-Min Tsai, a researcher at the University of Oxford in the U.K. and lead author of the paper explaining the origin of sulphur dioxide in WASP-39 b’s atmosphere. “I see this as a really promising outlook for advancing our understanding of exoplanet atmospheres with [this mission].”
Earth-like Bocaprins certainly is not. Bocaprins is an odd planet. It orbits very close to its host star and appears to be tidally locked—as the Moon is to Earth—so has one super-hot side and one super-cold. It’s actually eight times closer than Mercury is to our Sun, although it’s about 1.3 times greater in diameter than Jupiter.
“We observed the exoplanet with several instruments that together cover a broad swath of the infrared spectrum and a panoply of chemical fingerprints inaccessible until JWST,” said Natalie Batalha, an astronomer at the University of California, Santa Cruz, who contributed to and helped coordinate the new research. “Data like these are a game changer.”