How does Earth’s atmosphere affect the apparent locations at which we see stars?

The light from stars refracts slightly as it enters Earth’s atmosphere. Refraction is largest nearest the horizon. As a result the true position of the stars is a bit off from where we observe them. Refraction of light from the sun results in sunrise being slightly earlier than it would be without the atmospheric refraction, and sunset isslightly later. Refraction also distorts our view of the sun and moon when they are very close to the horizon.


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