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Positional Astronomy at Melbourne Observatory
Image: Album - Photographs
Source: Museum Victoria
Along with the observations required for timekeeping, positional astronomy occupied the largest part of the Observatory's work. Positional astronomy consisted of the accurate and repeated observations of stars, and then the reduction of the observations to provide a precise location of the star in the sky and its magnitude. When the Melbourne Observatory commenced, this involved the use of the transit telescope and accompanying equipment to fix the location. By the 1880s celestial photography had improved so that it was possible to take series of photos of the sky, then measure the position and magnitude of stars on the photographic plates.
The work of the Melbourne Observatory was of particular importance because it was one of the best equipped observatories in the southern hemisphere, and thus able to observe stars that could not be seen from the European and North American observatories.
In the early years Melbourne Observatory became involved in several international projects. In 1863 Government Astronomer Robert Ellery took observations of the parallax of Mars in conjunction with Greenwich Observatory near London and Pulkowa Observatory in St Petersburg; this was to provide measurements that would aid the calculation of the distance of the Earth from the Sun. The following year, in collaboration with Greenwich Observatory, the Observatory was making observations of the polar distances of stars, to measure the amount of apparent displacement due to the refraction of the Earth's atmosphere. Prior to the Transit of Venus in 1874, the Observatory made large numbers of transit observations of stars that would be used by expeditions from the northern hemisphere observatories to locate the precise position of their field observatories.
Several projects were aimed at measuring as accurately as possible the distances between the planets and the Sun, and therefore understanding the mechanics of the solar system. For example, in 1931 the Observatory used its astrographic telescope to photograph the passage of the minor planet Eros; the photographic plates were sent to Greenwich where astronomer Spencer Jones used them with those from other observatories to more accurately measure solar parallax. His work would not be improved upon until the advent of radio astronomy after the Second World War permitted radar measurements of the distance between Earth and Venus.
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Negative - Equatorial House & Photoheliograph House, Melbourne Observatory
8 inch equatorial house and photoheliograph house at Melbourne Observatory, from the north-east.
From: South Yarra, Australia Images: 1 -
Negative - Main Building, Melbourne Observatory, 1969
Main observatory building, Melbourne Observatory
From: South Yarra, Australia Images: 1 -
No Image Available
Coelostat - Paul Garnier
Coelostat made by Paul Garnier, Paris, and used at Melbourne Observatory. A coelostat reflects continuously the same region of the sky into the field of view of a fixed telescope. A mi ...
From: Paris, France Images: 0 -
Negative - Stevenson Thermometer Screen, Melbourne Observatory, circa 1879
Stevenson thermometer screen erected at Melbourne Observatory. Chain standard, erected in 1876, and tower of Government House visible in background. This photograph was possibly taken i ...
From: South Yarra, Australia Images: 1 -
No Image Available
Thermometer - Fahrenheit, Grimoldi
Fahrenheit thermometer, by Grimoldi, Melbourne. Range +20 to 120 degrees. Used at Melbourne Observatory.
From: Melbourne, Australia Images: 0 -
Negative - Timeball Tower, Williamstown
The timeball tower at Williamstown. A telegraph signal from Melbourne Observatory at precisely 1pm each day lowered the brass ball. This allowed ships in Hobson's Bay to correct their c ...
From: Williamstown, Australia Images: 1 -
Negative - Main Building, Melbourne Observatory, 1969
Main Building, Melbourne Observatory
From: South Yarra, Australia Images: 1 -
Negative - Sunshine Recorder erected at Melbourne Observatory
Sunshine recorder on roof of Main Building, Melbourne Observatory.
From: South Yarra, Australia Images: 1 -
No Image Available
Thermometer - Fahrenheit, Negretti & Zambra
Fahrenheit thermometer, made by Negretti & Zambra, London. Range -30 to +110 degrees. Used at Melbourne Observatory.
From: London, United Kingdom Images: 0 -
Negative - Jeffree Telescope, Melbourne Observatory, circa 1960
The Jeffree telescope in the Astrograph House at Melbourne Observatory, circa 1960. The Jeffree Telescope was built in the 1930s at the Bendigo Railway Workshops, and purchased by the ...
From: South Yarra, Australia Images: 1
