In the unlikely situation that you are caught unawares by the Sun being obscured by a large black circle, you are probably witnessing a solar eclipse, a rare event where our Moon is between us and the Sun (the other way round is a lunar eclipse). Eclipses can happen anytime there is a stellar body between two others, and are fairly spectacular to witness. As our understanding of orbits and physics increases we can better predict and observe these astronomically awesome events. 

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What is a supermoon?

Formally known as the perigee-syzygy of the Earth-Moon-Sun system, supermoons are lunar events that have a big effect on how we view the Moon.