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NXQXQ TIL In 1611, Johannes Fabricius and his father observed sunspots directly through a telescope shortly after sunrise or before sunset. They discovered that the Sun rotates by recording how sunspots moved around
VBoyp TIL Johannes Hevelius had exceptionally keen eyesight and could see stars of the seventh magnitude. He compiled a "Celestial Atlas" using both instruments, naked eye observations, and observed sunspots to accurately determine the solar rotation
OGMyR TIL Astronomer Rudolf Wolf observed sunspots through a telescope for 46 years from 1847 and managed to reconstruct historical records back to 1610. His sunspot number monitoring work continued at the Zürich Observatory until 1979