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The Transit of Venus is still a week away. But, it is good to prepare ahead of time. If you miss this transit, you will have to wait until 2117 to see the next one. That's not likely. There will probably be several diaries about the transit, or referring to it, in the coming week. Check them out. You won't want to miss this event. This diary give several links to useful information to help you prepare.

It starts just after 5 pm CDT June 5 and lasts for about 7 hours. The sun will set for most people in the continental US during the transit. Those farther west can see its entirety.

Yes, you do need to protect your eyes if you plan to view the sun directly.
Pinhole projection is safe without eye protection.

Come below the squiggle for more about planning for the transit.

What and When is a Transit?

Venus orbits the Sun at a distance that is closer than Earth. That means it orbits faster than Earth. It has been catching up to us and will pass us June 5th. When it does so this year, Venus will be seen in silhouette for a few hours from the Earth. This alignment is rare. It happened in 2004. Now in 2012. They occur in pairs. The last pair were in 1874 and 1882 and the pair before that were in 1761 and 1769. Next will be in 2117 and 2125. This is your last chance.

Video from NASA about the Transit

NASA presented a 4 minute video this week about the transit, some history, and some interesting facts. It is well worth a view.

1882 Transit Re-Animation

From Sky and the image at the right to see the full article and view the animation.
In late 1882, Massachusetts astronomer David Peck Todd traveled to California to photograph the transit of Venus from the summit of Mount Hamilton, where a solar photographic telescope made by the renowned optical firm Alvan Clark & Sons waited among the stacks of bricks and timbers from which Lick Observatory was rising. As the transit unfolded on December 6th, Todd obtained a superb series of plates under perfect skies. His 147 glass negatives were carefully stored in the mountain vault, but as astronomers turned to other techniques for determining the scale of the solar system, the plates lay untouched and were eventually forgotten.

Fast-forward 120 years. Spurred by a reference in one of Todd's letters in Lick's Mary Lea Shane Archives, all 147 negatives, still in good condition, were located at the observatory and made into an animation. To our knowledge, this collection of photos constitutes the most complete surviving record of a historical transit of Venus.

What Time Will it Happen Here?

The transit begins just after 5 pm CDT. That is late afternoon. It will last 7 hours. But the sun will set before that during mid-transit. Here is an online tool that will calculate the precise times for your specific location on a map. You can enter a location. Or, drag a red marker on the map to your location. Times are calculated for five transit events.

  • Exterior Ingress - when the disk of Venus first contacts the Sun
  • Interior Ingress - when the disk of Venus is fully within the disk of the Sun
  • Transit Center - when the disk of Venus is centered on the disk of the Sun
  • Interior Egress - when the disk of Venus starts to leave the disk of the Sun
  • Exterior Egress - when the disk of Venus last touches the disk of the Sun

That online tool is from a website that also offers an app for iPhone. The free app will allow individuals to send their observations of the 2012 transit of Venus to a global experiment to measure the size of the solar system.

With the Venus Transit app, it’s like you’re holding an almanac, an artificial transit device, a pendulum, a personal assistant to read the clock and a mailman – all needed by the eighteenth and nineteenth century astronomers observing the transit of Venus – in one hand!

How to View or Photograph

The transit will be viewable anywhere the sun is shining after 5 pm. Your local community and/or astronomy club might have an event planned. Those are always fun. Viewing glasses and telescope views are often available. Plus, getting lots of people together add to the fun.

You may safely use a pinhole viewer just as you did with the recent annular eclipse. But, the image will not be large or sharp. Keep the pinhole small to increase sharpness. Project onto the viewing card a few feet away away. Put it in a cardboard box to darken it. It will be a challenge to see the silhouette of Venus this way. Some have used binoculars to project a clearer image. Do NOT look through the binoculars.

You may use certified eclipse viewing glasses without worry. You will probably be able to see the small disk of Venus clearly this way with the naked eye.

If you are using more professional level equipment and want to photograph the transit, here is a fine article from Sky and Telescope giving more details about equipment needs, etc.

Where to Watch Online

For many, the best alternative will be to watch online. There are several sites which are planning to offer live streaming views online. One of my favorites is Slooh Space Telescope. They provided great coverage of the recent annular eclipse. The link provided has a count down clock. Click the SLOOH and be taken to their viewer. Just above the round viewer are left and right triangular arrows. Use them to see different video feeds if there are any at the time. Farther down the screen is information about past events.

Once again from Sky and Telescope, this article has links and descriptions about seven locations planning to provide live views. Since the transit lasts a long time, I suggest you drop in on these and see how their views differ.

As noted before, this is the last opportunity any of us will have to view a transit of Venus in our lifetimes. Don't let it pass. Nature is providing a free show of one of her beautiful events. Enjoy.
There are so many stars shining in the sky, so many beautiful things winking at you, but when Venus comes out, all the others are waned, they are pushed to the background.
— Mehmet Murat ildan from the play Galileo Galilei (2001)

Originally posted to SciTech on Tue May 29, 2012 at 08:10 AM PDT.

Also republished by J Town, Street Prophets , and Astro Kos.

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