Image of the start and end (inset) of transit of Venus taken on June 8th from the UK by S*T*A*R member Gavin Warnes. This event occurs so rarely that no living human had observed it until that day The next and last transit in our lifetimes occurs on June 5-6th 2012 but you will need to travel to see it. More details can be found at here. Transits of Mercury occur more often and will be visible on May 9th 2016 and November 11th 2019.
Transit of Venus