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In this month: September

Every month Elizabeth Cocking, long time member of Sydney City Skywatchers and current secretary, researches interesting historical occurrences and highlights people who contributed to our understanding of the cosmos who were born in the month. We hope you enjoy her findings.

1st September 1859

The first solar flare is observed independently by British astronomers Richard Carrington and Richard Hodgson. The flare was associated with a major coronal mass ejection (CME) that hit Earth's magnetosphere causing the largest geomagnetic storm on record. The storm, known as the Carrington Event, caused strong auroral displays - southern auroras were observed as far north as Queensland - and caused havoc with telegraph systems.

Carrington and Hodgson compiled independent reports which were published side-by-side in the Monthly Notices of the Royal Astronomical Society, and exhibited their drawings of the event at the November 1859 meeting of the Royal Astronomical Society. If a solar storm of this magnitude occurred today it would cause widespread electrical disruptions, blackouts and damage due to extended outages of the electrical grid. The solar storm of 2012 was of similar intensity, but it passed Earth's orbit without striking the planet, missing by nine days.

Solar flare: Image Credit: NASA/SDO/ Wiessinger

8th September 1911

The Oddie telescope is the first telescope to be installed at Mt Stromlo Observatory. The dome built to house it was the first Commonwealth structure to be erected in the newly established Australian Capital Territory.

The 9 inch Oddie refractor telescope was manufactured by Thomas Grubb around 1890 and was a donation from amateur astronomer James Oddie. It was initially used to test the suitability of the Mt Stromlo site as an Observatory. Astronomers used the telescope to measure the orbits of binary stars, search for remnants of supernovae in the Milky Way and take spectra of southern stars, gathering information on their age, size and chemical composition.

On the 18th January 2003 devastating bushfires hit Mount Stromlo destroying five telescopes including the Oddie, as well as workshops, seven homes, and the heritage-listed administration building.The telescope was reconstructed in 2011 (see image below of Judith Bailey with the reconstructed telescope on Mt Stromlo, Photo Toner Stevenson) and you can read more about the new Oddie telescope here.

Image T. Stevenson, 2011

28th September 1969

At approximately 10:58 a.m. local time on the 28th September 1969 a meteorite crashed in Victoria near Murchison, 160 km north of Melbourne scattering around 100 kg of fragments over an area larger than 13 square kilometres. In January 2020, astronomers reported that the meteorite’s silicon carbide particles have been determined to be 7 billion years old, 2.5 billion years older than the age of the Earth and the solar system, and the oldest material found on Earth to date.


18th September 1819

Jean Bernard Leon Foucault. French physicist. Best known for his demonstration of the Foucault Pendulum - a heavy iron ball swinging from a wire 67 metres long – which proves that the Earth rotates about its axis. For this demonstration and a similar one using a gyroscope, he received the Copley Medal from the Royal Society of London in 1855. Foucault also made an early measurement of the speed of light, finding a value within one percent of the true figure. He also discovered eddy currents, and is credited with naming the gyroscope. A copy of Foucault's pendulum is in the Pantheon in Paris, image below courtesy WikiCommons.

11th September 1847

Mary Watson Whitney. American astronomer. For twenty two years she was head of Vassar Observatory where 102 scientific papers were published under her guidance.

During her career she concentrated on teaching and research related to double stars, variable stars, asteroids, comets, and measurements by photographic plates.

She was a fellow of the American Association for the Advancement of Science, a charter member of the Astronomical and Astrophysical Society and a founding member of the American Astronomical Society. Mary Whitney also believed that science provided strong career opportunities for women. With such training, her students were able to find professional positions in observatories across the country. Image below of Vassar Observatory from the archives.

15th September 1938

James Walter Christy. American astronomer. On the 22nd June 1978 while working at the United States Naval Observatory, he, and colleague Robert Harrington, discovered that Pluto had a moon, which Christy named Charon after his wife. The name remained unofficial until its adoption by the IAU in 1986. The discovery was made by carefully examining an enlargement of a photographic plate of Pluto and noticing it had a very slight bulge on one side.

In 2008, the asteroid 129564 Christy was named in his honour.

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