The closest star to earth is Proxima Centauri, and is 4.2 light years away. But how do we know that? Before I explain, move your head left and right. What you'll notice is that things start to move like your computer screen and your keyboard, even your hands. This effect is called parallax. But you may also be thinking that it shouldn't work, because if you've watched the sun not move while you been in some sort of vehicle. Parallax actually does "move" the sun in this situation, but the difference is so small because it's farther away and you don't notice it.
Astronomers measure the distance to stars by using parallax. To measure Proxima Centauri we first look at the star once, and then do so again in six months. Then we make an imaginary triangle. The angle opposite from the base is how much the star moves. The base is just the diameter of earth's orbit. Then using high school trigonometry, we can measure the distance to our star using the imaginary triangle.
I got my information here, here and here.
Very interesting stuff Henry. I must admit I didn't know this. I'm glad you found 3 sources but remember Wikipedia is not a credible source. Try and find 1 more credible source on this subject.
ReplyDeleteIf Wikipedia is not a reliable source because anyone can post on it, then all sites are unreliable.
ReplyDeleteWe've talked a little bit about this in class. Here is another spreadsheet that you can use if you like to work through if a site is reliable or not. https://docs.google.com/a/branson.k12.mo.us/spreadsheet/ccc?key=0AvrcX2GA0W_AdGs4b0hOYmhUcGtoVjRXWEg5SjRzOEE&usp=sharing
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