This Day in Geek History: March 21
1684
Giovanni Domenico Cassini discovers Tethys and Dione, two moons of Saturn with a refractor telescope.
1859
The first Zoological Society is incorporated in Philadelphia, Pennsylvania. Following the disruption of the Civil War, the society will establish the country’s first Zoo.
1925
Wolfgang Pauli publishes his “exclusion principle” at the young age of twenty-four, in an article in the journal Zeitschrift für Physik. The Pauli exclusion principle states that two fermions, such as electrons, cannot be in the same quantum state at the same time. In 1945, Pauli will be awarded a Nobel Prize for this fundamental contribution to the science of quantum mechanics.
Read the rest of this entry » » »
In a letter, 
Alexander von Humoldt and