Kreidberg Uses New Planet Data from LHS 3844 b
Astronomers using the James Webb Space Telescope studied a new planet’s surface for the first time, turning infrared measurements of LHS 3844 b into a direct look at a rocky world nearly 50 light-years away. Laura Kreidberg, the principal investigator, said JWST can detect light coming directly from the surface of the distant planet.
She described the result plainly: “Thanks to the amazing sensitivity of JWST, we can detect light coming directly from the surface of this distant rocky planet.” The team’s measurements point to a dark, hot, barren rock, and Kreidberg said, “We see a dark, hot, barren rock, devoid of any atmosphere.”
Kreidberg’s JWST measurements
Kreidberg and her team observed three secondary eclipses in 2023 and 2024, using JWST’s Mid-Infrared Instrument, or MIRI, to measure infrared light emitted from the planet’s intensely hot dayside. LHS 3844 b is a super-Earth about 30% larger than Earth, discovered in 2019, and it orbits a cool red dwarf star in just 11 hours. The planet is tidally locked, so one side constantly faces its star while the other stays in darkness.
The dayside reaches about 1,340 degrees Fahrenheit, or 725 degrees Celsius. Rather than focusing on the atmosphere, the team analyzed heat coming from the surface, which is what let it draw conclusions about the rock itself.
LHS 3844 b and basalt
The data ruled out an Earth-like crust rich in silica and granite. They point instead to a surface dominated by basalt, a dark volcanic rock rich in iron and magnesium that is commonly found on the moon and Mercury. Sebastian Zieba said, “This planet likely only contains little water,” and the team said one possible explanation is a relatively young surface shaped by recent volcanic activity.
MIRI did not detect gases such as carbon dioxide or sulfur dioxide, leaving the planet classified as an airless world from the measurements taken so far. For astronomers, the practical change is direct: JWST can now pull surface information from a rocky exoplanet, not just atmospheric clues, and that opens a new way to compare distant planets with the rocky bodies already known in the solar system.
