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The Venus Transit 2004

Posted by timothy on from the romantic-encounter dept.

Walkiry writes "In just 47 days our friendly neighbour planet Venus will be passing right in between Earth and good ol' Sun, giving us the chance to see a small black spot going accross the disk (last one was in 1882). This is called the Venus Transit. The interesting thing is that there is a project asking for volunteers to perform their own measurements of the phenomena and submit their own results, in what will be the first accurate and public measurement of an extraterrestrial distance. Do you have a spare telescope and some free time on June 8th?"

4 of 199 comments (clear)

  1. low frequency of occurance! by ALLXSTHINGS · · Score: 5, Informative

    Apaprently, the next Venus transit after this one will be in 2012, but the next two after that won't be until 2117 and 2125. Looks like a once in a lifetime deal. (source: http://sunearth.gsfc.nasa.gov/eclipse/transit/venu s0412.html)

  2. Re:A small black spot on the Sun by NortWind · · Score: 5, Informative
    Okay, everybody stare directly at the Sun.
    You can glance at the Sun, or else all baseball fielders would be blind. However, if you're using a nice 8" reflector, even closing your eyelid is not going to help. They make metalized "solar filters" for many telescopes, which keep most of the energy out of the scope body while preserving the aperature so you can still have good resolution at high magnification.

    If you have a smaller telescope, or a a pair of binolculars, you can project an image of the sun onto a sheet of paper through the eyepiece. Use a cardboard box to make a darker area for the paper to be in. If there is some distance to the paper, the image of the Sun will be big enough that it will not burn the paper. Experiment with distance and focus to see what works.

    Or you can just buy a Solar Viewer. American Science & Surplus has 'em for under $100.
  3. Re:Of course we do by WalksOnDirt · · Score: 5, Informative

    I have a spare telescope and the free time, but I live in California.

    The west coast of North America and most of South America won't be able to see the transit.

    --
    a,e,i,o,u and sometimes w and y (at be if of up cwm by)
  4. Eye gouging vs wallet gouging by Latent+Heat · · Score: 5, Informative
    There are two kinds of telescope sun filters. An objective filter fits over the front end of the telescope. It filters light out before the light enters the telescopy. It is more expensive but the only safe kind.

    The other kind of sun filter fits over your eyepiece or inside your eyepiece. I once had a 2.4 inch refracting telescope that came with this piece of welder's glass that fit over the eyepiece. I never used it because I was warned not to.

    The advantage of the objective sun filter (the ones I have seen advertised are aluminized mylar) is that 1) it blocks out intense sunlight before it even gets to your telescope, and 2) it is exposed to no more than normal sun intensity because it hasn't been concentrated by the telescope.

    The wee bit of welder's glass at the telescope eyepiece is unsafe because it is getting the full focus of sunlight from the telescope and the thing and crack from the heat and then your eyeball is in peril.

    The other safe method is projection through the telescope on to a piece of paper. Safe for one's eyes -- I ruined my beginner's refractor doing that because the heat cooked a cheap plastic element in the one eyepiece it came with.