Events
in 1535
The Sun dog phenomenon observed over Stockholm and depicted in the famous painting "Vädersolstavlan".
Vädersolstavlan (Swedish for "The Sun Dog Painting") is an oil-on-panel painting depicting a halo display, an atmospheric optical phenomenon, observed over Stockholm on April 20, 1535. It is named after the sun dogs appearing on the upper right part of the painting. While chiefly noted for being the oldest depiction of Stockholm in colour, it is arguably also the oldest Swedish landscape painting and the oldest depiction of sun dogs.
Sun dog,
sun
in 1862
Louis Pasteur and Claude Bernard complete the first pasteurization tests.
Pasteurization (or pasteurisation, see spelling differences) is a process of heating a food, usually a liquid, to a specific temperature for a definite length of time and then cooling it immediately. This process slows spoilage due to microbial growth in the food.
pasteurization
in 1939
Billie Holiday records the first Civil Rights song "Strange Fruit".
"Strange Fruit" is a song performed most famously by Billie Holiday, who released her first recording of it in 1939, the year she first sang it. Written by the teacher Abel Meeropol as a poem, it exposed American racism, particularly the lynching of African Americans. Such lynchings had occurred chiefly in the South but also in all other regions of the United States. The writer, Abel, set it to music and with his wife and the singer Laura Duncan, performed it as a protest song in New York venues, including Madison Square Garden.
Billie Holiday,
Strange Fruit,
song
Births
in 1745
Philippe Pinel was a French physician who was instrumental in the development of a more humane psychological approach to the custody and care of psychiatric patients, referred to today as moral treatment. He also made notable contributions to the classification of mental disorders and has been described by some as "the father of modern psychiatry".

in 1808
Louis-Napoléon Bonaparte was the President of the French Second Republic and as Napoleon III, the ruler of the Second French Empire.
Deaths
in 1821
Franz Karl Achard was a German chemist, physicist and biologist. His principal discovery was the production of sugar from sugar beets.

in 1992
Benny Hill was an English comedian and actor, notable for his long-running television programme The Benny Hill Show.