Template:Are You Sure/September 20

1977: A series of celestial events occurs, with sightings reported over a vast territory, from Copenhagen and Helsinki in the west to Vladivostok in the east. It is commonly known as the The Petrozavodsk phenomenon after the city of Petrozavodsk in Russia (then in the Soviet Union), where a glowing object which showered the city with numerous rays was widely reported. The nature of the phenomenon is disputed.

• ... that mathematician and crime-fighter Gerolamo Cardano discovered a previously unknown class of Gnomon algorithm functions which detect and prevent crimes against Hypocycloids?

• ... that chemist and physicist James Dewar born. He will invent the vacuum flask, which he will use in conjunction with extensive research into the liquefaction of gases?

• ... that mathematician and academic Paul Erdős firmly believed mathematics to be a social activity, and that Erdős lived an itinerant lifestyle with the sole purpose of writing mathematical papers with other mathematicians?

• ... that mathematician Vera Faddeeva pioneered the field of linear algebra, andt that her Computational Methods of Linear Algebra (1950) will be widely acclaimed?