Do you know that next week’s Transit of Venus (when the planet Venus crosses the sun) will be the last in our lifetime? According to the Transit of Venus Australia website,
Transits of Venus occur in a pattern that repeats every 243 years with pairs of transits eight years apart separated by gaps of 121½ years and 105½ years. Venus and the Earth are aligned in the same direction out from the Sun about every 584 days (this is called in conjunction), however a transit does not occur each time because Venus’s orbit is usually above or below the Sun in the sky. Since the phenomena was first recognized there have only been six transits of Venus – 1639, 1761, 1769, 1874, 1882 and the most recent one in 2004. The 6th June 2012 transit is our last opportunity to observe a transit of Venus, as the next event occurs on 11th December 2117.