The 2012 Transit of Venus
by Paul Deans
|The June 8, 2004, transit of Venus at sunrise from an overlook above the Catawba River near Connelly's Springs, NC. Courtesy David Cortner.|
Two astronomers observed it in 1639. Hundreds viewed it in 1769. Hundreds of thousands of spectators caught at least a glimpse of it in 1882. No one knows how many millions -- perhaps even hundreds of millions -- witnessed it in 2004. And June 5/6, 2012, is your only opportunity to see it. So, where will you be during next year's transit of Venus?
The phrase "once in a lifetime" denotes a rare event. A Venus transit is actually a twice-in-a-lifetime event, because two transits occur within a span of eight years. But each transit pair is separated from the next (and previous) pair by more than a century. Since the invention of the telescope, only three transit sets have occurred: 1631 and 1639; 1761 and 1769; and 1874 and 1882. The current pair (2004 and 2012) concludes next year. Miss 2012, and you'll have to wait 105 years -- until December 11, 2117 -- for the start of the next transit pair (2117 and 2125).
Why so rare? It's all in the tilt.
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