Timeline of solar astronomy

Timeline of solar astronomy

9th century

* 850 - Ahmad ibn Muhammad ibn Kathīr al-Farghānī (Alfraganus) gives values for the obliquity of the ecliptic, the precessional movement of the apogees of the Sun

10th century

* 900-929 - Muhammad ibn Jābir al-Harrānī al-Battānī (Albatenius) discovers that the direction of the Sun's eccentricity is changing, which in modern astronomy is equivalent to the Earth moving in an elliptic orbit around the Sun
* 950-1000 - Ibn Yunus observes more than 10,000 entries for the Sun's position for many years using a large astrolabe with a diameter of nearly 1.4 metres

11th century

* 1031 - Abū al-Rayhān al-Bīrūnī calculates the distance between the Earth and the Sun in his "Canon Mas’udicus"

17th century

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

19th century

* 1802 - William Hyde Wollaston observes dark lines in the solar spectrum
* 1814 - Joseph Fraunhofer systematically studies the dark lines in the solar spectrum
* 1834 - Hermann Helmholtz proposes gravitational contraction as the energy source for the Sun
* 1843 - Heinrich Schwabe announces his discovery of the sunspot cycle and estimates its period to be about a decade
* 1852 - Edward Sabine shows that sunspot number is correlated with geomagnetic field variations
* 1859 - Richard Carrington discovers solar flares
* 1860 - Gustav Kirchhoff and Robert Bunsen discover that each chemical element has its own distinct set of spectral lines and use this fact to explain the solar dark lines
* 1861 - Gustav Spörer discovers the variation of sun-spot latitudes during a solar cycle, explained by Spörer's law
* 1863 - Richard Carrington discovers the differential nature of solar rotation
* 1868 - 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 - Edward Maunder discovers the 1645-1715 Maunder sunspot minimum

20th century

* 1904 - Edward Maunder plots the first sunspot "butterfly diagram"
* 1906 - Karl Schwarzschild explains solar limb darkening
* 1908 - George Hale discovers the Zeeman splitting of spectral lines from sunspots
* 1929 - Bernard Lyot invents the coronagraph and observes the corona with an "artificial eclipse."
* 1942 - J.S. Hey detects solar radio waves
* 1949 - Herbert Friedman detects solar X-rays
* 1960 - Robert B. Leighton, Robert Noyes, and George Simon discover solar five-minute oscillations by observing the Doppler shifts of solar dark lines
* 1961 - Horace W. Babcock proposes the magnetic coiling sunspot theory
* 1970 - Roger Ulrich, John Leibacher, and Robert Stein deduce from theoretical solar models that the interior of the Sun could act as a resonant acoustic cavity
* 1975 - Franz-Ludwig Deubner makes the first accurate measurements of the period and horizontal wavelength of the five-minute solar oscillations
* 1981 - NASA retrieves data from 1978 that shows a comet crashing into the Sun

21st century

*2004 - largest solar flare ever recorded occurs