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yesterday

Webb Maps the Surface of a Nearby Super-Earth, Revealing a Dark Basaltic World

The mid-infrared reading opens a new way to read rocky exoplanet geology.

Image
This high-resolution photo of the planet Mercury probably resembles the rocky exoplanet LHS 3844 b. Results from JWST observations favour an airless rocky planet with a dark, basalt-like surface, likely space-weathered by irradiation and meteorite impacts. © NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington (cropped)
image: ©INchendio | iStock
Webb Telescope Maps Bare Rock on Distant Super-Earth, Finds No Signs of Tectonic Activity

Overview

  • Using JWST’s Mid-Infrared Instrument, researchers isolated heat from LHS 3844 b’s dayside and produced one of the first direct geological spectra of a rocky exoplanet.
  • The spectrum best matches dark basalt or mantle-like rock and rules out a silica-rich continental crust that on Earth forms through water-driven plate tectonics.
  • MIRI saw no sulfur dioxide linked to active volcanism, which favors an old, space‑weathered surface coated in darkened regolith over a freshly repaved lava plain.
  • The team combined JWST data from 5 to 12 micrometers with earlier Spitzer measurements and will use new Webb observations to test angle-dependent emission that can separate solid rock from loose dust.
  • LHS 3844 b is about 30% larger than Earth, orbits a red dwarf every 11 hours at 48.5 light-years, reaches roughly 1,000 Kelvin on its dayside, and offers a cautionary case for close-in rocky worlds that lose air, water, and Earth-like tectonics.