2012 Transit of Venus

So, most of you have probably heard vaguely of this, but I suspect most people don't actually know what's going to happen in a few weeks. So, I'll basically say this. The last transit of Venus you'll see in your lifetime (Unless you manage to live for the next 105 years) is going to happen on the 5th or 6th of June (Depending on your timezone). What does this mean? I'll go into more detail in a sec, but basically, the planet Venus is going to pass over the face of the sun, similar to a solar eclipse.



Firstly, the basic science behind this. As you're probably aware, there are a bunch of planets in our solar system, of which we're the third, as demonstrated by this poorly done Paint drawing:

You're probably also aware how a solar eclipse works. The moon comes between us and the sun, and the moon casts a shadow on the earth, so if you look at the sun (Incidentally, don't do that, it's not good for you), you can't see the sun because the moon is in front of it.

The transit of Venus is more or less the same thing. Venus comes between us and the sun. Except, well, while Venus is considerably larger than the moon, it's also much further away, so it appears much smaller to us in the sky. How much smaller? Well, you've all seen the moon, what with it being the second brightest object in the sky behind the sun. Venus is the third brightest. Usually, you can see it early in the evening or in the morning (Hence why it's sometimes known as the morning or evening star) as a really bright star. Yeah. That little thing that looks like a star is Venus. That's how much smaller than the moon it is.

Not really to scale.

So naturally, Venus isn't going to block out all the sun's light like the moon can. Instead, what we see is a small dot moving across the face of the sun. In addition, because Venus is so far away, the transit lasts much longer than an eclipse. In total, it's going to take 6 hours for Venus to fully cross the sun.

An image from the 2004 transit of Venus

Because Earth and Venus don't have properly aligned orbits, transits of Venus happen in pairs, 8 years apart, and each pair having at least 100 years between them. We had a transit in 2004, so after this one, we don't have another until 2117. Which is kinda a long way away. So make the most of this! This is a once (or twice if you saw the one in 2004, as has been pointed out to me. :P) in a lifetime opportunity, so don't let it go to waste!

When can you see it?
Well, you can use this handy website that I'm linking on these words right here or, for those in New Zealand like me, about 10:15am to 4:45pm on Wednesday, the 6th of June.

How can you see it?
Obviously, looking directly at the sun is kinda a really really bad idea. Don't do it. Really. If you can, try get a pair of solar viewing glasses. I've been trying, but they're not easy to get your hands on, what with the transit being a couple of weeks away, and the northern hemisphere getting a nice solar eclipse the other day. If you have a local observatory, they may be able to help. If you can't, make your own viewer! How? Well, a little googling got me this website: http://www.exploratorium.edu/eclipse/how.html

They offer two different methods to make projectors. Firstly, a pinhole box type system which seems like the better option:


There are safe ways to view the sun. The simplest requires only a long box (at least 6 feet long), a piece of aluminum foil, a pin, and a sheet of white paper.
The length of the box is important. The longer the box, the bigger the pinhole image. To find the size of the image, multiply the length of the box by the number 0.0093. For a box that is 1 meter long, the image will be 0.0093 meters (or 9.3 mm) in diameter. If your box is 5 feet (60 inches) long, your solar image will be 60 x 0.0093 = 0.56 inches in diameter. If you want to round things off, the size of the image is about 1/100th the length of the box.
If you can't find a long box or tube, you can tape together two or more boxes to make a longer one. In the illustrations below, we found that taping together two triangular UPS shipping tubes works well. Of course, if you do this, you must cut out the cardboard at the ends of the tube in the middle!


1) Find or make a long box or tube.

(Click on the image for expanded instructions)
2) Cut a hole in the center of one end of the box.
3) Tape a piece of foil over the hole.
4) Poke a small hole in the foil with a pin.


(Click on the image for expanded instructions)
5) Cut a viewing hole in the side of the box.


(Click on the image for expanded instructions)
6) Put a piece of white paper inside the end of the box near the viewing portal.
Point the end of the box with the pinhole at the sun so that you see a round image on the paper at the other end. If you are having trouble pointing, look at the shadow of the box on the ground. Move the box so that the shadow looks like the end of the box (so the sides of the box are not casting a shadow). The round spot of light you see on the paper is a pinhole image of the sun. Do not look through the pinhole at the sun! Look only at the image on the paper.

Secondly, a cheap, but should still be effective, option that just uses two pieces of paper.

(Click on the image for expanded instructions)
If you want, you can use only two pieces of cardboard--one piece colored white to project on to, and the other with a pinhole. Hold up the pinhole as far from the screen as you can. Remember, the farther you are from the screen, the bigger your image.

Thank you, random website!

Don't miss this opportunity. You won't get another chance to see this, unless medicine makes some more huge leaps forward. I'll be doing my best to make sure I get some nice wee pictures going on myself.


Links
Wikipedia article on the 2012 Transit of Venus
Official website for it, comes with a handy Android/iPhone app