Template:Selected anniversaries/June 18
1178: Five Canterbury monks see what is possibly the Giordano Bruno crater being formed. It is believed that the current oscillations of the Moon's distance from the Earth (on the order of meters) are a result of this collision.
1348: Physician and academic Gentile Gentili da Foligno dies. Da Foligno was among the first European physicians to perform a dissection on a human being (1341).
1922: Astronomer and academic Jacobus Kapteyn dies. Kapteyn conducted extensive studies of the Milky Way using photography and statistical methods to determine the motions and distribution of stars, discovering evidence for galactic rotation.
1974: Mathematician and academic Júlio César de Mello e Souza dies. He is well known in Brazil and abroad by his books on recreational mathematics, most of them published under the pen names of Malba Tahan and Breno de Alencar Bianco.