It’s a fill in the blank each element will produce a line pattern in either an absorption or emission spectrum. this is very useful to astronomers because each line pattern is like a allowing astronomers to identify the presence of certain in the atmosphere of stars based on the patterns of

Each element will produce a unique/distinct line pattern in either an absorption or emission spectrum. This is very useful to astronomers because each line pattern is like a fingerprint, voice-print, or government-issued photo-ID, allowing astronomers to identify the presence of certain elements in the atmosphere of stars based on the patterns of emission or absorption lines in the star's spectrum.

the closer the planet is to the sun, the larger the gravity

54 degrees incident angle = reflected angle

angle is from normal turned to line of ray