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The Transit of Venus, 2012

Credit: Geoffrey Wyatt, Sydney Observatory/Powerhouse Museum

Geoffrey Wyatt’s prize-winning image of the 2004 transit was taken with a special filter that only allows through the red light of hydrogen atoms. Credit: Geoffrey Wyatt, Sydney Observatory/Powerhouse Museum

By Nick Lomb

Transits of Venus allowed astronomers to calculate the scale of the solar system, and led to the discovery of Australia. On 6 June this year Australians and New Zealanders will have a ring-side view of one of the most famous events in astronomy – and the last one for another 105 years.

Dr Nick Lomb spent 30 years as an astronomer at Sydney Observatory, which is part of the Powerhouse Museum, and is still closely associated with it. His book Transit Of Venus: 1631 to the Present is published by NewSouth and Powerhouse Publishing, and provides the full story of the transits of Venus (see http://www.sydneyobservatory.com.au/transit-of-venus-the-book/). Sydney Observatory will run programs associated with the transit of Venus on 6 June 2012, including safe solar viewing if sky conditions permit. For details, see http://www.sydneyobservatory.com.au/transit-of-venus-at-the-obs/

The full text of this article can be purchased from Informit.

Next month the planet Venus will pass in front of the Sun for the last time until the year 2117. This event is the rare and famous transit of Venus, which has only been seen six times in recorded history – the first sighting was in 1639 and the last in 2004.

Transits of Venus are of exceptional significance to Australians because the voyage of James Cook that led to the settlement of the country by the British was to observe the transit of June 1769 from Tahiti. To astronomers of the

18th and 19th centuries, transits of Venus were of great importance as they provided an opportunity to measure the distance to the Sun and hence the scale of the solar system. In order to make the necessary observations for this measurement, astronomers undertook daring and adventurous journeys to far-flung places such as Tahiti, Siberia, India and South Africa.

Only Mercury and Venus – the two planets that circle the Sun within the path of the Earth – can ever be seen in transit across the face of the Sun. Transits of Mercury are more common as they occur on average 13 times each century. Those of Venus generally occur in a pair of transits 8 years apart, and then not for a century or more.

17th Century Transits
German astronomer and mathematician Johannes Kepler was the first to predict the possibility of transits by predicting the transits...

The full text of this article can be purchased from Informit.