IS IT possible that if not for the rare celestial event of Venus moving across the face of the sun, Captain Cook may not have noticed Australia?
That's arguable, and Paul Brunton, the senior curator of the Mitchell Library at the State Library of NSW, will enlarge on the theory that the transit of Venus was instrumental in the discovery of Australia at a talk he's giving in Goonellabah tonight (Thursday, May 17).
The planet Venus is going to cross the sun again on June 6, a rare event (although when it's happened once, it usually happens a second time within the following eight years) - but then it won't happen again for another 100 years.
Which means that anyone who sees it on June 6 is unlikely to see it again.
It will take two-and-a-half hours to complete the transit.
Back in the glory days of Britain's foremost scientific body, the Royal Society, it was understood that by recording the transit from various locations, it was possible to calculate the distance of the earth from the sun.
This would yield information about the size of the solar system, the distances between planets and the distances of the stars from the earth - all jolly useful for navigation in the days before GPS.
So back in the 1760s, the Royal Society petitioned King George III for funds to send an expedition to the South Seas to observe the transit of June 3, 1769.
The King gave them the kingly sum of 4000 pounds, the government provided a vessel and crew, and James Cook was chosen to lead the expedition in the Endeavour.
We don't want to spoil Paul Brunton's story by telling you everything that happened next, but suffice to say that Australia was glimpsed on this expedition.
The 27-year-old Joseph Banks was on board, and not 10 years later it was Banks who proposed the east coast of Australia be considered a suitable location to which to transport Britain's convicts.
Mr Brunton will show a copy of the document in which Cook recorded the transit of Venus, and his original calculations.
All are welcome to the talk on the transit of Venus at the Goonellabah Community Centre tonight at 7.30pm.