In the midst of an election season that—like so many others—is being billed as “the most important in our lifetimes”—something much bigger—literally cosmic—is happening that should remind us of how insignificant our issues actually are. The event is the transit of Venus, a rare astronomical occurrence that will take place on Wednesday, June 5, 2012. It will be visible in parts of North America, Europe and in Hawaii. If you can’t be there in person with special solar glasses and telescopes, you can watch it live on NASA’s website.
What’s this all about? For the astronomy-challenged—like me—the transit of Venus occurs when Venus crosses in front of the Sun and is visible from Earth. When it happens, Venus appears as a distinct, but small disc, moving slowly across the vast expanse of the Sun. Transits of Venus are rare—rarer even than Halley’s Comet, which comes around in 76-year cycles. Only six transits of Venus are known to have been observed by humans: in 1639, 1761, 1769, 1874, 1882 and 2004.
Transits come in pairs. This week’s transit is the second part of a pair that started in 2004. But the pairs are widely spaced. Before 2004, the previous pair of transits was in 1882. The next pair will be in 2117. So, unless you were literally born yesterday and plan to live to be 105, this is your last chance to see this phenomenon.
What’s the big deal? Looking out into the sky has been a human fascination for millennia, and what we’ve seen has made us think beyond ourselves, as well as sparking scientific discoveries and many controversies [with associated religious heresies].
The transit of Venus plays a big role in scientific history. According to a fascinating history of the phenomenon, in 1663, Rev. James Gregory who was considered one of the most important mathematicians of the 17th century, suggested that a more accurate measurement of the Earth-Sun distance could be made using the transit of Venus. Sir Edmund Halley, the namesake for Halley’s Comet, made the same suggestion 14 years later in 1677 and published an important paper on the details of this technique in 1716.
That measurement is known as the Astronomical Unit, by the way—which would make a really good trivia question.
During later transits, astronomers used more advanced measuring techniques to refine that number, and in 1891, the Astronomical Unit was set at 92,797,000 miles, plus or minus 59,700. Then, in the 1960s, scientists began bouncing radar off Venus during the transit, eventually yielding today’s super-precise Astronomical Unit as 92,955,820.3 miles, with an uncertainty of 1.5 kilometers.
The transit of Venus is, of course, just one of many astronomical events—like solar and lunar eclipses—that literally illuminate our place in the universe. In a solar eclipse, we see our own shadow on the sun. In a lunar eclipse or a transit of Venus, we observe indisputable evidence of the order of the solar system. For some, the effect is to confirm a belief in a supreme being who created all of these things. For others, like me, it sparks self-awareness of my tiny place in a huge universe, a desire to know more, and amazement at the courage and curiosity of those early stargazers who changed human consciousness with their dogged devotion to knowledge and science.
But whether you see the hand of a deity in all of this or not, the upcoming transit of Venus surely forces all of us to see daily lives and our petty, partisan political behaviors in perspective—as part of something vastly bigger than ourselves. And that’s a world view that needs reinforcing.