Earth was cooler than usual in the 16th and 17th centuries and scientists are still trying to figure out why. New analysis of sunspot drawings by Kepler, in 1607, may shed some light.

These 17th-century drawings of the sun by Kepler add fire to solar cycle mystery

Source: space
Source Link: https://www.space.com/sun-johannes-kepler-sunspots-drawings-solar-cycle