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  • Elizabeth Cocking

In this month: May

13 May 1861

John Tebbutt discovers the Great Comet of 1861, also known as Comet C/1861 J1, one of the most brilliant comets known. He sent letters to the Government Astronomer at Sydney Observatory, Rev. William Scott, and to the Sydney Morning Herald newspaper advising of his find. However, at the time there was no means of sending the news quickly to England and when the comet became visible in the northern hemisphere on 29 June 1861 it was a complete surprise to the astronomers in Britain and elsewhere. Tebbutt was acknowledged as the first discoverer of the comet, and the first to compute its approximate orbit. More info here. Image courtesy wikimedia commons of the Great Comet of 1861, also known as C/1861 J1 or comet Tebbutt; drawing by E. Weiss

Great Comet 1861

3 May 1715

A total solar eclipse occurs. Known as Halley's Eclipse, after Edmund Halley (of Comet Halley fame) he predicted the totality of this eclipse to within 4 minutes accuracy (it actually lasted for 4 minutes and 14 seconds), and drew a map showing the path of totality across Great Britain. He observed the eclipse from the Royal Society’s building in London on a morning with a sky of “perfect serene azure blew” (sic).

5 May 1933

The New York Times newspaper announces the discovery by Karl Jansky of radio waves apparently coming from the centre of our galaxy. The news was widely publicized, Jansky was keen to continue investigating these mysterious cosmic signals and many scientists were fascinated by his discovery, but no one followed up on it for several years. It was during the Great Depression and observatories could not afford take on any new projects. Today the “jansky” is the unit of measurement for radio wave intensity.


10 May 1900

Cecilia Payne-Gaposchkin. British born American astronomer who proposed in her doctoral thesis that stars were composed primarily of hydrogen and helium. Her ground breaking conclusion was initially rejected because it contradicted the scientific wisdom of the time which held that there were no significant elemental differences between the Sun and Earth. Independent observations eventually proved that she was correct.

14 May 1908

Joseph Lade Pawsey. Australian radio astronomer. Widely acknowledged as the “father” of radio astronomy in Australia, he was an outstanding leader and got Australian radio astronomers to use a process called interferometry. In early 1946 he began observations with the sea interferometer at Dover Heights, Sydney. Within a few days one of the largest groups of sunspots ever recorded began its transit across the Sun’s disc causing major disruptions to radio communications on Earth. His observations proved that the strong radio emission originated from the vicinity of the sunspots.

The crater Pawsey, on the Moon, is named after him.

16 May 1925


Nancy Grace Roman. American astronomer and one of the first female executives at NASA. She was the first Chief of Astronomy in NASA's Office of Space Science and the first woman to hold an executive position at the space agency. She is known to many as the "Mother of Hubble" for her role in planning the Hubble Space Telescope. Before her work at NASA while working at Yerkes Observatory she observed the star AG Draconis and discovered that its emission spectrum had completely changed since earlier observations. The publication of her discovery substantially raised her profile within the astronomical community contributing to her career progression. Throughout her career, Roman was also an active public speaker and educator, and an advocate for women in the sciences. Image above: Dr. Nancy Grace Roman, NASA's first Chief of Astronomy, is shown at NASA's Goddard Space Flight Center in Greenbelt, Maryland, in approximately 1972.Credit: NASA

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