Crossing of Venus historic sight for Pacific
A rare planetary event occurs this week - the transit of Venus. More than 240 years ago it led British mariner James Cook into the Pacific Ocean to set up an observatory in Tahiti.
Wednesday's transit, one of the rarest astronomical events in the solar system, will not happen again for more than a century.
It occurs when the planet crosses the sun.
Historically, it was important because it enabled the distance between the earth and sun to be measured.
Professor Fred Watson from the Australian Astronomical Observatory says it is important to Australia, because it is why Captain Cook sailed on his first voyage south for Britain.
He claimed a number of Pacific islands for his country, sailed around New Zealand, visited the Australian east coast, and passed Batavia, now Jakarta, on his way home.
Professor Watson said the Venus transit "happens in pairs, actually, separated by eight years and then the next one's more than a century away.
"But of course its transit, historically, is why we speak English in Australia, rather than French, because it's why Captain Cook went to Tahiti in 1769 and then on to explore the coast of New South Wales."
There will also be a partial eclipse of the moon on Monday night that Professor Watson says will look - in a clear sky - as if a bite has been taken out of the moon.