In this month: May

2nd May 1780

Sir William Herschel discovers the first binary star, Xi Ursae Majoris, also named Alula Australis, in the constellation of Ursa Major. It was the first visual double star for which an orbit was calculated. Xi Ursae Majoris is found in the left hind paw of the Great Bear

Pluto: Image credit NASA/ John Hopkins University

1st May 1930

Pluto (picture above) is officially named. Discovered on the 18th February 1930 by Clyde Tombaugh at Lowell Observatory Pluto receives its name from an eleven year old schoolgirl, Venetia Burney. On the announcement Venetia received £5 as a reward. Pluto is named for the Roman god of the underworld. In 2006, the International Astronomical Union downgraded Pluto to dwarf planet status. By the way, Walt Disney named Mickey Mouse’s dog Pluto after the planet, not the other way around ! Image above taken by New Horizons when it made its closest approach to Pluto on 14 July 2015. Image Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute

20th May 1990

The Hubble Space Telescope sends its first image back to Earth, a binary star HD96755 in NGC 3532, 1,300 light years away. Although the image exceeded that of the best ground-based telescopes, scientists realised something was wrong when the images weren't as sharp as they should be. A NASA investigation discovered that the telescope's 8-foot primary mirror had been ground too flat around the edges. Several missions to repair the telescope were done and Hubble has gone on to take some of the most detailed and spectacular images ever seen.

BORN

25th May 1834 John Tebbutt. Australian astronomer, and the man on the first Australian $100 note. Born at Windsor, NSW, he was Australia’s most famous nineteenth century astronomer and was famous for discovering the "Great Comet of 1861". He was the first president of the New South Wales branch of the British Astronomical Association, later Sydney City Skywatchers.

Williamina Fleming supervising Harvard College astronomers

15th May 1857

Williamina Fleming. Scottish astronomer. During her career, she helped develop a common designation system for stars and catalogued thousands of stars and other astronomical phenomena. She is also noted for the discovery of the Horsehead Nebula in 1888. The image above shows Ms Fleming supervising the team of women who determined spectra and measured magnitudes at Harvard College Observatory. Credit: Harvard College Observatory

11th May 1924 Antony Hewish. British radio astronomer. He won the Nobel Prize for Physics in 1974 for his role in the discovery of pulsars. One of his PhD students, Jocelyn Bell (later Jocelyn Bell Burnell), noted the radio source which was ultimately recognised as the first pulsar.