It was not Galileo Galilei or Thomas Harriot but Johannes Kepler who left the earliest datable sunspot drawing. An international team led by Nagoya University in Japan has made a significant breakthrough by re-examining Kepler's legacy records from 1607. Using modern techniques, they measured the sunspot group position and applied Spörer's law, which describes the tendency for average sunspot latitudes to migrate closer to the Sun’s equator during each cycle, to demarcate the boundaries of...
