Which method is used to study the atmosphere of exoplanets?

Which method is used to study the atmosphere of exoplanets?

• A. Transit photometry
• B. Spectroscopy
• C. Radial velocity
• D. Direct imaging

Answer: (B)

Spectroscopy is used to study exoplanet atmospheres because it reveals the chemical fingerprints of gases. When light from the star passes through a planet’s atmosphere during a transit, atoms and molecules absorb light at specific wavelengths, creating distinctive absorption features in the spectrum. By analyzing these features, scientists identify which gases are present (such as water vapor, sodium, or methane) and can infer temperatures and abundances. Emission or reflected light from the planet can also be analyzed spectroscopically to learn about the dayside composition and structure. Transit photometry alone measures how much light is blocked and mainly tells us about size and orbit, while radial velocity tracks stellar motion due to gravity, and direct imaging, though capable of providing spectra in some cases, is less routinely used for detailing atmospheric composition.

Spectroscopy is used to study exoplanet atmospheres because it reveals the chemical fingerprints of gases. When light from the star passes through a planet’s atmosphere during a transit, atoms and molecules absorb light at specific wavelengths, creating distinctive absorption features in the spectrum. By analyzing these features, scientists identify which gases are present (such as water vapor, sodium, or methane) and can infer temperatures and abundances. Emission or reflected light from the planet can also be analyzed spectroscopically to learn about the dayside composition and structure. Transit photometry alone measures how much light is blocked and mainly tells us about size and orbit, while radial velocity tracks stellar motion due to gravity, and direct imaging, though capable of providing spectra in some cases, is less routinely used for detailing atmospheric composition.