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Observing the Transit of Venus

In a couple of weeks, Venus will once again transit the face of the sun, on June 5th and 6th specifically. The last transit was in 2004, but this won’t happen again in our lifetimes. The next transit will not be until 2117, well into the 22nd century. It would be interesting to observe this, but I am not aware whether it can be observed with ordinary equipment, such as you can make for viewing a solar eclipse. Does anyone know much about how one would observe a phenomena like this absent a very expensive solar telescope?

18 Responses to “Observing the Transit of Venus”

  1. Robb Allen says:

    I’m not sure you’d be able to see it without a telescope. I mean, you could grab a solar filter meant for telescopes and just look through it, but I don’t think you’d be able to make out much more than the sun as a dot and Venus would be too small to see.

  2. NevynPA says:

    You can build a pinhole box, get a solar filter for a regular telescope, or use a telescope as a projector. Good information and links for all of them can be found at:

    http://solar-center.stanford.edu/observe/

  3. Andy B. says:

    I’ll amplify Robb’s guess: Does anyone know if Venus is large enough to see with ordinary equipment? I’ve tried looking at it with my (cheap, 50-year-old) 60X spotting scope, and it looked like a tiny circle, but I’m not sure I was seeing “it,” or the best my scope could do with resolution of a concentrated light source.

    I remember looking at sun spots quite clearly, back in the ’50s, with a pair of good 10X binoculars and the dark glass from an arc welder’s helmet. If Venus is big enough to see with whatever magnification you have available, that might work.

    • Robert says:

      A tiny circle is about all you’ll see with anything but the largest telescopes, and with them all you can see is a somewhat larger circle. Venus has constant cloud cover, so you can’t make out any surface detail.

      It does have phases, though, just like the moon.

      A small telescope with a GOOD solar filter should suffice to watch the transit. And by GOOD filter I mean something that covers the objective and not just the eyepiece, and is well enough constructed that it won’t crack in the heat. 50-60x should be plenty of magnification.

  4. Stranger says:

    Venus is definitely large enough to see without equipment. It is about the size of a pinhead at arms length when it is the morning or evening star.

    The very simplest equipment that provides a good view of a transit is a variation of the “pinhole camera” type equipment used by 16th century astronomers, a piece of foil on one end of a “dark box” with a white screen in the other, with a “dark cloth” over a viewing port.

    The size of the pinhole will vary with the distance from the pinhole to the screen, but too small a pinhole will degrade sharpness as will too large a pinhole. Fortunately we are not forced to use gold foil for that.

    If the black dot of Venus in silhouette is too small, a magnifying glass near the viewers eye will enlarge it, although with some reduction in sharpness.

    If you want to get fancier, find a small telescope, a filter, and place a cheap web camera where you get the best view. You can enlarge the image to suit you, and there’s no risk to your one set for a lifetime eyes.

    Stranger

  5. PT says:

    Welding mask and some binoculars?

    • Alpheus says:

      I like the idea. I don’t know how safe it is–hopefully someone else can explain that–but it’s a good idea, nonetheless!

      UPDATE: Apparently someone in a later comment does this, at least for eclipses.

  6. Jethro says:

    This site lists 6 different ways of varying quality.
    http://www.transitofvenus.org/june2012/

  7. It is small enough that you are probably going to want a small telescope–even the cheap 60mm refractors that you can find at garage sales work fine. BUT you need a solar filter that goes over the end of the telescope. These aren’t hideously expensive, especially the aluminized Mylar ones sold by Kendrick Astro. You can some sunspot pictures I took yesterday using one of these at http://claytonecramer.blogspot.com/2012/05/sunspots.html.

  8. Easiest may be the on-line webcams. Here is one such link:

    http://sunearthday.nasa.gov/2012/transit/webcast.php

  9. NUGUN says:

    I’ve got a telescope. I’ve also got some Mylar bags. I wonder if I can construct a filter from the bags?

    Thoughts?

    • It depends. How much do you value your eyesight?

      Solar filters are in short supply at the moment because of the eclipse visible across much of the U.S. next Sunday.

  10. SPQR says:

    The best way to observe this is to find a good local astronomy club and join them. They’ll have an event to observe, and lots of people with great equipment will be set up and probably happy to share views.

  11. Billll says:

    I use my welders helmet for eclipses and the like. You could probably get a workable photograph by placing the helmet over your camera.

  12. Cap'n Bob says:

    We’re having an annular eclipse here in Arizona on the 20th of May. I have been practicing solar photography using filters from Rainbow Symphony and getting pretty good results.

    http://capnbob.us/blog/2012/05/12/another-big-sunspot/
    http://www.rainbowsymphonystore.com/solar-filters.html

  13. HSR47 says:

    In the past, I once used undeveloped fully exposed film to view a solar eclipse. It wasn’t particularly sharp, but I could see what was going on.

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