Timeline of solar astronomy

10th century

900Ã¢ÂÂ929 Ã¢ÂÂ Muhammad ibn JÃÂbir al-HarrÃÂnÃÂ« al-BattÃÂnÃÂ« (Albatenius) discovers that the direction of the Sun's eccentricity is changing

1613 Ã¢ÂÂ Galileo Galilei uses sunspot observations to demonstrate the rotation of the Sun
1619 Ã¢ÂÂ Johannes Kepler postulates a solar wind to explain the direction of comet tails

1802 Ã¢ÂÂ William Hyde Wollaston observes dark lines in the solar spectrum
1814 Ã¢ÂÂ Joseph Fraunhofer systematically studies the dark lines in the solar spectrum
1834 Ã¢ÂÂ Hermann Helmholtz proposes gravitational contraction as the energy source for the Sun
1843 Ã¢ÂÂ Heinrich Schwabe announces his discovery of the sunspot cycle and estimates its period to be about a decade
1852 Ã¢ÂÂ Edward Sabine shows that sunspot number is correlated with geomagnetic field variations
1859 Ã¢ÂÂ Richard Carrington discovers solar flares
1860 Ã¢ÂÂ Gustav Kirchhoff and Robert Bunsen discover that each chemical element has its own distinct set of spectral lines
1861 Ã¢ÂÂ Gustav SpÃÂ¶rer discovers the variation of sun-spot latitudes during a solar cycle, explained by SpÃÂ¶rer's law
1863 Ã¢ÂÂ Richard Carrington discovers the differential nature of solar rotation
1868 Ã¢ÂÂ Pierre Janssen and Norman Lockyer discover an unidentified yellow line in solar prominence spectra and suggest it comes from a new element which they name "helium"
1893 Ã¢ÂÂ Edward Maunder discovers the 1645-1715 Maunder sunspot minimum

1904 Ã¢ÂÂ Edward Maunder plots the first sunspot "butterfly diagram"
1906 Ã¢ÂÂ Karl Schwarzschild explains solar limb darkening
1908 Ã¢ÂÂ George Hale discovers the Zeeman splitting of spectral lines from sunspots
1925 Ã¢ÂÂ Cecilia Payne proposes hydrogen is the dominant element of the Sun, not iron
1929 Ã¢ÂÂ Bernard Lyot invents the coronagraph and observes the corona with an "artificial eclipse"
1942 Ã¢ÂÂ J.S. Hey detects solar radio waves
1949 Ã¢ÂÂ Herbert Friedman detects solar X-rays
1960 Ã¢ÂÂ Robert B. Leighton, Robert Noyes, and George Simon discover solar five-minute oscillations by observing the Doppler shifts of solar dark lines
1961 Ã¢ÂÂ Horace W. Babcock proposes the magnetic coiling sunspot theory
1970 Ã¢ÂÂ Roger Ulrich, John Leibacher, and Robert F. Stein deduce from theoretical solar models that the interior of the Sun could act as a resonant acoustic cavity
1975 Ã¢ÂÂ Franz-Ludwig Deubner makes the first accurate measurements of the period and horizontal wavelength of the five-minute solar oscillations
1981 Ã¢ÂÂ NASA retrieves data from 1978 that shows a comet crashing into the Sun