The Sun and the Origins of the Solar System

The Sun and the Origins of the Solar System — page 7
The Sun and The Origins Of The Solar System sunspots and established the period as 11 years Wolf also introduced what is termed the Zurich relative relative sunspot number a value equal to the sum of the spots plus 10 times the number of groups which is still used today Illustration from Galileo’s History and Demonstrations Concerning Sunspots and Their Properties or Letters on Sunspots Sunspots 1613 Much of the work at this time was carried out by wealthy amateurs such as Richard Christopher Carrington of Britain who built a private observatory and discovered the differential differential rotation and the equatorward drift of activity during a sunspot cycle He was the first with another Englishman R Hodgson to observe a solar flare Photographic monitoring monitoring began in 1860 and soon spectroscopy was applied to the Sun so elements present in the Sun and their physical physical state could begin to be investigated In the early part of the 19th century Joseph von Fraunhofer mapped the solar spectrum At the end of the 19th century spectroscopy during eclipses revealed the character of the atmosphere but the million-degree coronal temperature was not established 12