Astrophysics

The dark and featureless surface of rocky exoplanet LHS 3844 b from JWST mid-infrared spectroscopy

Sebastian Zieba, Laura Kreidberg

Featured May 18, 2026

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Simply

Scientists used JWST to study a hot, rocky exoplanet, finding its surface is dark and rocky, like our Moon, with no thick air or fresh volcanoes, by matching its heat fingerprint to different rock types and gases.

In depth

This paper leverages JWST's mid-infrared spectroscopy to directly characterize the surface and atmospheric properties of the rocky exoplanet LHS 3844 b. By comparing the planet's thermal emission spectrum to a comprehensive library of rocky surface models and atmospheric gas models, the authors determined that LHS 3844 b possesses a dark, low-silica surface, likely basaltic and space-weathered, while ruling out the presence of a thick atmosphere or significant volcanic outgassing.

Key Takeaways

1
JWST mid-infrared spectroscopy enables the direct characterization of rocky exoplanet surfaces and atmospheres, providing insights into their geological history.
2
The exoplanet LHS 3844 b exhibits a dark, low-silica surface (e.g., basalt or olivine-rich materials), consistent with an old, space-weathered regolith.
3
The observations strongly disfavor thick atmospheres and significant volcanic outgassing of CO $_{2}$ or SO $_{2}$ , suggesting an airless or very tenuous atmospheric state.

Conceptual Flow

HIGH LEVEL

Methodology: How was it done?

Scientists used a powerful space telescope to measure the planet's heat signal, then compared it to many computer models of different rocks and air types to figure out what the planet is made of.

Planet's Heat Signal

Compare to Models

Surface & Air Type

Results: What did they find?

They found the planet has a dark, rocky surface, like a moon that's been hit by space dust for a long time, and it doesn't have a thick atmosphere or active volcanoes.

Dark, Rocky Planet

No Thick Air

Old, Weathered Surface