In 1908, American astronomer George E. Hale discovered the presence of the magnetic field in sunspots, and in 1917, a systematic observations of sunspot magnetic fields begun at Mount Wilson Observatory (MWO). In early 1950s, the first photoelectric magnetograph was developed by H. W. Babcock, and soon after, a number of magnetographs was developed in several countries around the globe. In mid-1960s, regular observations of full disk longitudinal magnetograms started at MWO, and in early 1970s, the full disk magnetograph observations begun at the National Solar Observatory at Kitt Peak. This dataset continues using Vector SpectroMagnetograph (VSM) on Synoptic Optical Long-term Investigations of the Sun (SOLIS) platform. Since 2010, the full disk magnetogams are observed by Helioseismic and Magnetic Imager (HMI) on board of Solar Dynamics Observatory (SDO). In this talk, I briefly review history and methods of observations of magnetic fields on the Sun, and discuss major discoveries in long-term studies of the photospheric magnetic fields.
Mode of presentation: oral (Need to be confirmed by the SOC)