Webb Telescope Creates First Climate Maps of Rocky Exoplanets

First Climate Maps of Alien Worlds

Astronomers have achieved a landmark in exoplanet science by producing the first detailed climate maps of Earth-sized rocky worlds beyond our solar system. Using NASA's James Webb Space Telescope, an international team continuously tracked the two innermost planets of the TRAPPIST-1 system in infrared light for sixty hours, covering a full orbit of each world.

Scorched Days, Frozen Nights

The results, published in Nature Astronomy, reveal a stark divide between the permanent day and night sides of TRAPPIST-1b and TRAPPIST-1c. Both planets are tidally locked, meaning one hemisphere permanently faces their host star while the other is cast in eternal darkness. TRAPPIST-1b's dayside exceeds two hundred degrees Celsius, whilst TRAPPIST-1c reaches nearly one hundred degrees. Both planets plunge below minus two hundred degrees on their nightsides, a contrast of more than five hundred degrees that points to virtually no heat redistribution between hemispheres.

No Atmospheres Detected

The extreme temperature swings strongly disfavour atmospheres with surface pressures of one bar or more for either planet. If these worlds once possessed atmospheres during their formation, the intense ultraviolet radiation and energetic particle fluxes from their red dwarf host star likely stripped them away entirely. The findings align with earlier Webb measurements showing TRAPPIST-1d also lacks an Earth-like atmosphere.

Hope for TRAPPIST-1e

Attention now turns to the outer planets in the system. Webb is currently observing TRAPPIST-1e, which orbits within the habitable zone where liquid water could theoretically exist. Early hints suggest it may possess a nitrogen-rich atmosphere, though more observations are needed to confirm. The TRAPPIST-1 system, located just forty light-years from Earth and celebrating the tenth anniversary of its discovery this year, continues to serve as a crucial reference system for understanding rocky worlds around red dwarf stars.