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On this day in 1572 – November 6th – Tycho Brahe recorded his observation of a bright new star (now listed as supernova SN 1572) in the constellation Cassiopeia.

The understanding of the time was that the stars were part of a sphere which was perfect and unchangeable, so the new object was assumed to be a local phenomenon. However, Tycho's study showed that it was a distant object.