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Astrophysics

Helium escaping from the atmosphere of a nearby rocky exoplanet orbiting in a habitable zone

Collin Cherubim, Shreyas Vissapragada

Featured July 23, 2026

Original Paper

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Simply

Scientists found a rocky planet is losing its air, specifically helium, showing that even planets in the "just right" zone can have their atmospheres stripped away, and this escape can change over time.

In depth
This paper presents the first definitive detection of atmospheric escape from a rocky exoplanet, LHS 1140b, located in its star's habitable zone. Using near-infrared transit spectroscopy, the authors observed metastable helium absorption, indicating a helium-dominated upper atmosphere depleted in hydrogen. The study also reveals time-variable atmospheric escape, suggesting dynamic processes influencing exoplanet atmospheres.

Key Takeaways

  • 1
    The study provides the first definitive evidence of atmospheric escape from a rocky exoplanet, LHS 1140b, located within its star's habitable zone.
  • 2
    Observations of metastable helium absorption indicate that LHS 1140b's upper atmosphere is dominated by helium and significantly depleted in hydrogen.
  • 3
    The detection of helium in 2024 but not 2025 suggests time-variable atmospheric escape, likely driven by changes in stellar XUV flux or upper atmosphere temperature.

Conceptual Flow

HIGH LEVEL
1
Methodology: How was it done?

Scientists watched a planet pass in front of its star, measured how the star's light changed, and used computer models to figure out what the planet's escaping air was made of.

Star Light
Planet Passes
Collect Light
Light Changes Data
2
Results: What did they find?

They discovered a rocky planet is losing helium from its upper air, which is surprising, and this air loss changes from year to year.

Rocky Planet
Losing Air
Helium Escape