Astronomy and Space

Planets and Moons

How can an observer distinguish planets from stars?

In general, planets emit a constant light or shine, whereas stars appear to twinkle. The twinkling effect is caused by the combination of the distance between the stars and Earth and the refractive effect Earth’s atmosphere has on a star’s light. Planets are relatively closer to Earth than stars and their disklike shapes average out the twinkling effect, except when they’re observed near Earth’s horizon.


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