JWST Maps Surface of Super-Earth LHS 3844 b in Historic First

A Giant Mercury 50 Light-Years Away

Imagine a giant Mercury 50 light-years away—a scorching, airless world perpetually baking under the glare of its host star. For the first time in history, astronomers have moved beyond analyzing exoplanet atmospheres to directly studying the surface geology of a rocky world beyond our solar system. Published on May 4, 2026, in Nature Astronomy, this groundbreaking JWST super-Earth surface 2026 study focuses on LHS 3844 b, a tidally locked planet completing an orbit every 11 hours.

First Exoplanet Surface Study: Breaking New Ground

Using the James Webb Space Telescope's Mid-Infrared Instrument (MIRI), an international team led by Sebastian Zieba of the Harvard-Smithsonian Center for Astrophysics (CfA) and Laura Kreidberg of the Max Planck Institute for Astronomy (MPIA) achieved the impossible. They captured the thermal emission from the planet's day side, allowing them to map its geological composition. "We see a dark, hot, barren rock, devoid of any atmosphere," stated Laura Kreidberg, confirming the planet's stark reality.

Among the discoveries, researchers identified several key geological traits:

• Basaltic Composition – The MIRI data definitively rules out an Earth-like granitic crust, pointing instead to a surface covered in dark basalt or hardened lava rock.
• Total Lack of Atmosphere – The temperature distribution across the planet's day side perfectly matches a bare rock model, confirming the absence of even a thin atmospheric envelope.
• Tidal Locking Effects – With one side constantly facing its red dwarf star, the day side reaches blistering temperatures capable of melting certain rocks, while the night side remains in a permanent deep freeze.

This LHS 3844 b discovery represents a monumental leap in exoplanetary science. Previously, telescopes could only infer surface properties or analyze thick gas envelopes. Now, these JWST MIRI rocky exoplanet observations prove we can directly probe alien geology.

Space Weathering and the Future of Exoplanet Geology

Because LHS 3844 b lacks a protective atmosphere, its surface is completely exposed to the harsh radiation and stellar winds of its host red dwarf. This continuous bombardment leads to a phenomenon known as space weathering, which dramatically alters the planet's outermost layer.

Key factors contributing to the planet's dark, barren surface include:

• Regolith Darkening – Constant stellar wind exposure causes iron and carbon particles in the alien soil to darken over millions of years, contributing to its low reflectivity.
• Micrometeorite Impacts – Without an atmosphere to burn up debris, microscopic impacts continuously churn and melt the surface rock, creating a glassy, dark regolith similar to our Moon.
• Volcanic History – The widespread presence of basalt suggests the planet may have experienced extensive volcanic activity in its past, flooding the surface with dark lava.

This first exoplanet surface study is just the beginning. Future JWST observations are already planned to target similar rocky worlds, promising to unveil the diverse geological tapestry of our galaxy. As we continue to refine our instruments, the dream of mapping alien continents and volcanic plains is rapidly becoming a reality.