Venus and the sun to align today for first time in 122 years!
The transit of Venus occurs today - this is the passage of the planet Venus across the face of the Sun. It last happened about 122 years ago (so probably no living person has seen it, or if they did, they probably don't remember). It will happen again in 8 or 12 years and then not again for another 120+ years.
The Transit of Venus is of historical significance to Australians, as the voyage by (then) Lt James Cook to Tahiti to observe the transit of 1769 had this as the primary goal. A search for the mythical southern continent was the subject of sealed, secondary, orders he opened after succeeding in observing the transit - the discovery of New Zealand and what is now New South Wales followed.
The reason that Cook (and others) travelled to the southern hemisphere to observe this was to ensure good viewing conditions. The outcome of the observations was for the purpose of obtaining the first accurate estimate for the distance of the Earth from the Sun - Cook got it to within 200,000Km, which isn't bad considering the relatively primitive instruments he had - the distance is 149,597,892 Km - he was out by 0.1%! A more accurate measurement wasn't obtained until the invention of radar in the middle of the 20th century. Even with radar, the orbital characteristics of Venus played a part as you can measure the distance from Earth to Venus by reflecting radar off Venus, but you bounce radar of the Sun as it just ain't a reflector of anything.