First photo of the transit of Venus for 2012, an event that will not be repeated in our lifetimes, taken at 9.45 am Melbourne time, June 6, 2012.
Venus is the small dark spot over the face of the sun.
The observation of this transit was one of the key scientific objectives in the 1760s. The science of astronomy was still young.
Uranus wasn’t discovered until 1781. Neptune was discovered in 1846. Pluto was discovered in 1930.
The outermost planet in the solar system was therefore still Saturn. This was the known limit of the solar system. But how big did that make the solar system?
Attempts had been made to do the calculation. Actually, astronomers in the islamic countries had found a way of calculating this several hundred, perhaps a thousand years earlier. But the most advanced European scientists were still working on this project.
A key piece of information was to be obtained by observing the transit of Venus. This is where Venus passes in front of the Sun as seen from the earth. The problem is, this only happens extremely rarely.
From wikipedia: “Transits of Venus occur in cycles of 243 years with the current pattern of transits being pairs of transits separated by eight years, at intervals of about 105.5 years or121.5 years.”
So, in recent times, we had this transit, and another one 8 years ago, in 2004. The one before that was way back in December 1882.
The transit of Venus in 1761 was a failure due to overcast weather in Europe.
If the European scientific community wanted to observe the Venus transit in 1769 they would need to send someone all the way to the other side of the world, to Tahiti. In those days, that was a serious expedition. It required an expert navigator. Captain James Cook was such a man.
Cook’s secondary, though perhaps no less important mission, revealed to him after he completed his observations, was to sail further south. There had been stories of a ‘great southern land’ that had never been discovered.
Cook’s journey led to the discovery of Australia in 1770. Thus, Australia was claimed and subsequently settled by the British. And as they say, the rest is history.
This second photo was taken around 11.30 am in Melbourne. (Image colour adjusted to compensate for filters used.)
Text and Photos © Rainer Rollfink, 2012, updated 2014
