Quote:
Originally Posted by alnorth
Today I was wondering how the hell we could know how far away stars are, and when I looked it up, the answer was pretty obvious. There's also a technique involving measuring brightness and color, but for most stars that aren't incredibly far away, we just use basic trigonometry. Measure the angle of a star, wait 6 months for the earth to be on the other side of the sun, measure the angle again, and do the math. Since we know the diameter of our orbit, thats all you really need.
The angle measurements obviously have to be extremely precise because we're talking about something that is ludicrously far away compared to our orbit. After about 400 light years we apparently lack the ability to measure the angle with enough precision to use the simpler trig method.
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This kind of reminds me of a dumb friend of mine (not calling you dumb). He asked how fast our planet spins, so I looked it up and we're spinning at 1000mph at the equator, but also moving at 66,000mph around the sun, while our entire solar system is moving at 560,000mph through the galaxy.
He then said "there's no way anyone could know that". So we looked up how this information was ascertained and then he didn't believe that. So I had to explain to him that just because you don't believe or understand how something happens it doesn't change the fact that it's actually happening.
I later told him to look into the inner workings of an automatic transmission just to see if he would be too afraid to drive his car.