German astronomer who was the first to measure the periodicity of the sunspot cycle. This may be considered as marking the beginning of solar physics.
Schwabe was born in Dessau, studied at Berlin, and worked as a pharmacist. In 1829 he sold his pharmacy and became an astronomer. He published 109 scientific papers and left 31 volumes of astronomical data to the Royal Astronomical Society.
Schwabe began to watch the Sun in 1825 with a 5-cm/2-in telescope and noticed sunspots, making daily counts of them for most of the rest of his life. In 1843 he was able to announce a periodicity: he declared that the sunspots waxed and waned in number according to a ten-year cycle.
In 1827 Schwabe rediscovered the eccentricity of Saturn's rings, and in 1831 he drew a picture of the planet Jupiter on which the Great Red Spot was shown for the first time.