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In this month - April 2018

Portrait of Isaac Newton by Godfrey Kneller 1869

28 April 1686 Isaac Newton presents his book Principia to the Royal Society. Widely regarded as one of the

greatest works in the history of science it covers Newton's laws of motion, and his law of

Universal Gravitation.

Yuri Gagarin collection, Star City, Moscow photo T. Stevenson

12 April 1961 Yuri Gagarin, Russian cosmonaut, becomes the first human to travel into space aboard Vostok 1. His flight started the “Space Race” of the 1960’s between Russia and the USA.

24 April 1990 The Hubble Space Telescope is launched. Named after the American astronomer Edwin Hubble. After a correction to the optics it has gone on to take stunning photos. It is still in operation orbiting at an average distance of 550km above Earth.


14 April 1629 Christian Huygens born. Dutch astronomer, physicist and mathematician. Famous for his work on Saturn’s rings and discovering its moon Titan.

28 April 1900 Jan Oort. Dutch astronomer. Made significant contributions to the understanding of the Milky Way and was also a pioneer in the field of radio astronomy. The Oort Cloud, a disc shaped cloud surrounding the solar system and believed to be the origin of long period comets, is named after him

28 April 1906 Bart Bok. Dutch born American astronomer. Lived in Australia 1957-1966 during which time he was Director of Mt Stromlo Observatory. He was also instrumental in establishing the Siding Spring Observatory and creating the Graduate Program in Astronomy at the ANU. Bart and Priscilla Bok, who was also a scientist, often stayed at Sydney Observatory as guests of the government astronomer, Harley Wood, and his wife, Una.

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