September 13, 2021

Today in 1912, Horace Welcome Babcock was born. Babcock was an American astronomer who invented a number of astronomical instruments, including a magnetograph which took measurements of the Sun’s magnetic field. This technique was also used to measure the magnetic fields of other stars and discovered that some stars are magnetically variable.

(Illustration) The solar magnetic field near solar maximum, in 2014. The structure is complex, with closed and open field lines poking out all over – ideal conditions for solar explosions. Credits: NASA’s Goddard Space Flight Center/Bridgman