earthlings have the unique advantage of living on a planet from which a large moon has the virtually identical apparent diameter as the sun—an extraordinarily rare scenario in planetary systems. During a total eclipse, the moon completely and exactly occludes the disc of the sun, while allowing us to observe its full corona. Observations on these carefully timed occasions have been instrumental in the development of spectroscopy, a field that not only allows us to understand the composition of and processes occurring in the sun but has also led to the development of stellar astrophysics. In
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