How are astronomers able to determine information about the chemical composition of an exoplanet's atmosphere?
a By measuring the amount of redshift and blueshift present in a planet's light, astronomers are able to identify the relative density of the planet, and then identify the elements it contains.
b Atmospheric data is one aspect of exoplanets that astronomers have not yet been able to measure.
c By measuring changes in the spectrum of a star during an exoplanet transit, astronomers may sometimes measure stronger absorption lines than from the star alone. These absorption lines can be used to infer the chemical composition of the planet's atmosphere.
d By measuring light that planets emit, astronomers are able to identify the chemical composition of an atmosphere by looking at specific emission lines.