Wednesday, June 06, 2012

Guided Venus Transit in Anchorage at UAA

I'd been hearing the stories, but wondering if Alaska would have a good view and how to watch without burning my eyeballs. It's been cloudy so we probably wouldn't see anything anyway. But I saw an announcement that telescopes and viewing glasses would be available on the garage roof behind the Integrated Sciences building at the University of Alaska Anchorage. Alaska and Hawaii are the only two states where the whole transit would be visible.  We're west enough that the sun wouldn't set before it was finished. And it was sunny.  And I had a nearby viewing spot with experts to guide me.  How could I not go?   But better go before it clouds over. (There were thin clouds, but I think you could see it the whole time.)  Told a friend to go and grabbed a neighbor who was reading in the sun.

There was a variety of telescopes - from the University and from local astronomy buffs.    I got there a little before midpoint.  There was a line to look into the fattest telescope.  People guessed they were there because there was a line.  Someone else suggested that 'bigger is better.'  The other telescopes didn't have lines.  And there were different ways to see Venus crossing the sun.

If you look closely you can see the dot that's Venus in the upper left and lower right images.   Here's another view with Physics/Astronomy post-doc Michelle Wooten answering people's questions.
Venus is the black dot near the bottom of the sun here.  With the telescopes that didn't show the sun directly, the images were flipped over.  Venus was actually going across the top.

Here I put my camera into the eyepiece of a telescope. (The telescope had a dark filter on it so people wouldn't hurt their eyes.)  The dot of Venus is near the top.

Then we went to the planetarium nearby to hear a talk on the phenomenon we were watching live.

I forgot to check the program at the door when I left to get the astronomer's name and I couldn't find a program with names on the UAA website.  Sorry. [UPDATE June 7:  Dr. Andy Puckett, the Planetarium Director and an Asst Prof of Astronomy at UAA introduced himself in a comment below.  Thanks, Andy!]  In the brief video below he shows Venus transiting across the sun and talks about the four contact points - as Venus first touches the sun from the outside, as it touches the edge from the inside, then after crossing the sun, as it touches the edge from the inside (third contact) and from the outside (fourth contact.)  The video ends when he says, now I'll tell you why this is important.

It's important, he goes on to say, because by measuring this transit time from different places on earth, by calculating the small differences in time of the four contact points, you can calculate the distance Venus is from the sun.  He asked us all to stick our arms out with our thumbs up and to close one eye as we put our thumb over some object.  Then switch eyes.  There's a jump and if you know the distance between your eyes, you can calculate the distance to the object.  I remember back to geometry being amazed at the ways you could figure out the third side of a triangle and I think that's what this does.

He also pointed out that when scientists went around the world to watch the second (1761) and third (1769) known transits (a couple of  people saw in 1639) there was no photography yet and the best time keepers were grandfather clocks with pendulums.  So they took grandfather clocks to keep track of time. 

This was a neat illustration on the ceiling of the planetarium.  It shows, if I understood this right, the orbit of Venus (the circle), the sun (the orange dot in the center) and the location of the earth (the blue 'earth'). Actually there are two earth locations - one on the upper left and one in the lower right (harder to see).  These would be on opposite sides of the earth's orbit around the sun.  There's a point on each side of Venus' orbit, where Venus lines up between the earth and the sun so that a transit is visible.  The white lines bounced back and forth to show where Venus would be in relation to the earth.  I think he said 13 orbits of Venus for every eight of earth.  So Venus hits the sweet spot, then misses for eight years, then hits it again.  Then it's over 100 years before it hits it again.

There are lots of places online where you can get more details.  Here's a site that looks at the history of sightings of Venus transits.  


  1. I was the speaker at the planetarium show you saw. My name is Dr. Andy Puckett, and I'm the Planetarium Director and an Asst Prof of Astronomy at UAA. I'm glad you liked what we had to offer! And great blog coverage. Thanks for the photos, videos, and great reviews.

  2. Thanks Andy! (I hope first name is ok.) The talk was fascinating. When I first saw the Dr. Andy Puckett, I was expecting a correction of my interpretation of what you said. Whew!


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