When an exoplanet transits a star, additional absorption lines appear at wavelengths associated with methane (CH_4) and water vapor (H_2O) What can scientists infer based on the additional absorption lines?

During a transit, some starlight passes through the exoplanet’s atmosphere before reaching us. Methane and water vapor absorb light at characteristic wavelengths, so their additional absorption lines indicate that these gases are present in the planet’s atmosphere. The lines do not show that the star produces these molecules through fusion.

AI-written and checked against the verified answer.