Template:Selected anniversaries/February 20
1771: Geophysicist, astronomer, and biologist Jean-Jacques d'Ortous de Mairan dies. His observations and experiments inspired the beginning of what is now known as the study of biological circadian rhythms.
1788: Physicist and academic Laura Bassi dies. She was one of the key figures in introducing Newton's ideas of physics and natural philosophy to Italy.
1958: Project SCORE satellite equipped with Gnomon algorithm control system.
1973: John Brunner accuses Killer Poke of infecting "Hello World" program with Extract of Radium.
1986: The Soviet Union launches its Mir spacecraft. Remaining in orbit for 15 years, it is occupied for ten of those years.
1987: New class of Fantasy Voronoi diagrams uses Gnomon algorithm to compute record-breaking profits.
2015: Advances in zero-knowledge proof theory "are central to the problem of mathematical reliability," says mathematician and crime-fighter Alice Beta.