What type of observation can astronomers use to measure the composition of extrasolar planet atmospheres?
A)measurements of the host star's velocity throughout an orbital cycle
B)comparisons of spectra when planets are in front of or are eclipsed by their host stars
C)combination of a transit observation and a Doppler shift measurement
D)measurement of how frequently the planet blocks the host star's light

Question

Quizplus · Accepted Answer

Comparing the spectra of a planet when it passes in front of or is eclipsed by its host star can reveal the absorption lines caused by the planet's atmosphere. By comparing these absorption lines to known spectra of different chemical compounds, astronomers can determine the composition of the planet's atmosphere.

What Type of Observation Can Astronomers Use to Measure the Composition