Yrjö Väisälä was a Finnish astronomer and physicist.
His main contributions were in the field of optics, but he was also very active in geodetics, astronomy and optical metrology. He had even an affectionate nickname of Wizard of Tuorla (Observatory/Optics laboratory), and there is a book with the same title in Finnish describing his works. Yrjö Väisälä discovered 128 asteroids. He used to name them with the names of his personal friends that had birthdays. One of them was the professor Matti Herman Palomaa, after whom an asteroid 1548 Palomaa was named. For this reason the Palomar Mountain Observatory in California has never had an asteroid bearing its name – the rules for naming asteroids state that the names have to differ from each other with more than one letter. His research group discovered 7 comets and 807 asteroids. The crater Väisälä on the Moon is named after him, and so are the asteroids 1573 Väisälä and 2804 Yrjö. The Tuorla Observatory was established in 1952 by the professor.
A bronze medal was issued in 1972 at the 20th anniversary of the establishment of the observatory. On the obverse the facade of the observatory building is pictured, with stars, clouds and a comet. Legend around "INGENIO LABORE VIRTVTE", meaning "(by) talent, work, virtue".
The reverse shows the left facing portrait of the founder Yrjö Väisälä, who was born in 1891 and died in 1971, soon before this medal was issued. The medal has an engraving in its rim: "INSTITUT ANGEWANTE GEODASIE és KULTATEOLISSUUS", refers to the issuer institute.