986: Death of the Persian astronomer Abd al-Rahman al-Sufi (known in the West as Azophi). Author of the famous Book of Fixed Stars, he corrected and updated Ptolemy's catalogue with an accuracy unrivalled for the time. He was the first to document the existence of the Andromeda Galaxy (which he described as a "little cloud") and the Large Magellanic Cloud (reported by navigators), long before the invention of the telescope.

1865: Birth of Pieter Zeeman in Zonnemaire. A Dutch physicist, he discovered in 1896 the effect that bears his name: the splitting of spectral lines under the influence of a magnetic field. This discovery, which earned him the Nobel Prize in Physics in 1902, revolutionised astronomy by allowing the remote measurement of the magnetism of the Sun, stars, and sunspots.

Image credits : Unknown author, ca. 1920