But how do we *KNOW* that?
5/20/2012 7:07 AM
A friend had a birthday party last night, and she asked me to bring one of my telescopes. I showed partygoers Saturn and a a few other objects. Although I wasn't part of this conversation, a couple people were discussing "How do you KNOW that?" - for example, if the Earth if round, or some other metric of astronomy. Those are interesting things to ponder of course, and the basis for rational and critical thinking. It forces us to consider what is true and what is not, and to me anyway, it serves as the basis for me accepting the things that astronomers tell me, as opposed to believing that they are involved in some giant conspiracy and attempting to fool the world about various things in our Universe.
One of the things I wound up having a conversation about was how far away, on average, most stars are from each other. A light year alone is a difficult concept to fathom. It's even harder to fathom how long it actually takes to get to one with present technology, given that Star Trek "warp speed" is something that still only exists in science fiction. But I was explaining how if you took every star in our Milky Way galaxy, and placed all equidistant from each other, then reduced each star to the size of a grain of salt, what the distance between each grain of salt would be.
I love the answer for this. SEVEN MILES. (That's about 11 kilometers.)
So I was perusing one of my favorite forums for astronomy, and came across a post that I thought did a wonderful job of explaining how astronomers know how far away stars are. Rather than try to explain it myself, I'll let this video do it instead, because I think it is really well done. Check it out here on Vimeo.