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Mass Transit
The Solar System >
On June 8, for everyone on this planet who can see the skies, Venus will pass in front of the sun for the first time since 1882. It is one of those phenomena for which nearly everyone on the planet cares ... well ... cares little or nothing quite frankly.
But for a lover of the skies things are different. He or she gets the same warm tingly feeling of excitement as a birdwatcher that finally spots that rare Hawaiian honeycreeper in the rain forest on the windward side of Maui's Haleakala Crater. It almost never happens in a lifetime.
Did I say everyone would be able to see it? That was sort of not altogether entirely true. Of all the places on earth, the only major locations to miss it are the southern tip of South America, and tiny New Zealand. And --- I can barely bring myself to write this --- North America west of the Rockies will miss it, too. Woe is us!!!
As nearly the entire human race gets a chance to experience this cosmic dance, we are literally left in the dark. We will miss all four "contacts" of the tiny planet as it silhouettes across the great face of the sun. There is no chance for us to see the famous "blackdrop affect," the time when the petite planet's disk arrives at the edge of the giant sun, and the shadow of Venus seems to reach out and touch the limb of our star.
So let's make the most of it from where we are, OK?
The reason Venus travels in front of the sun at all is, of course, because the planet is in an orbit between the sun and us. But the laws of physics are set up so that she takes a mere 224 of our days to travel around the sun once --- a venerian year --- so this passing in front, this "transit," should happen much more often, correct?
Earth's and Venus' orbits are slightly tipped relative to each other so Venus doesn't always pass directly in front of the sun as she passes us on her inside lane. Most of the time the cloudy planet moves by just over or just under the sun. You may recall that the Moon's orbit doesn't always take it directly in front of the Sun, either, causing the famous solar eclipse. Venus' transit really is a rare event; no one alive has seen one.
It's time to use the imagination to see the Big Picture and put it all in perspective. Venus is about to pass in front of the Sun, in just days. You may have noticed Venus already; she's the extremely bright planet in the west after the sun goes down. The more observant among us may have noticed Venus getting lower and lower in the skies over the last month or so.
Go outside just after sunset and look to the west. Make sure no one is watching you, then tilt your head far to the right to get a better idea of Venus' orbital path as she passes by us. Imagine that Venus is moving in its orbit toward the just set sun. Watch in the next days as the Evening Star gets closer and closer to the sun, finally disappearing into its brightness in the day or two before the transit.
Though we won't be able to see the crossing, we can see it live over the internet. Check out The Exploratorium's excellent site.
After Venus passes by to the "other side" of the sun, we will soon be able to see her again! But now she will rise before the sun rises in the morning, and now she will be called the Morning Star. Watch in the coming weeks as Venus rises earlier and earlier, higher and higher.
Yes, we are completely left out of this transit, but mark your calendars for June 5, 2012. Through another coordination of the orbits of our planets, we in Southern California get our chance to see a transit that afternoon. But you'd better see it then because it will have to last a lifetime --- the next one isn't until 2117!
Mark Ritter teaches astronomy at Temecula Valley High School and can be reached at mritter@firstlightastro.com.
Posted by Administrator at 2004.06. 6 12:32 PM | Comments (0)
