Brahe, Tycho (1546-1601)
Brahe was a Danish astronomer who discovered a new star (a nova) in the constellation of Cassiopeia in 1572. The star was so bright it was visible during the day. This appearance challenged the inherited wisdom of their predecessors, who claimed the stars were eternal and unchanging.
A new observatory was built in Copenhagen, Denmark to study what this appearance of a new star might mean. Brahe made good use of this new observatory and devoted all his time to remeasuring the 788 stars of Ptolemy's great star catalog. Once all the stars were remeasured this new map became the first complete, modern stellar atlas.