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bipolarber -> RE: If you were a Science Teacher.... (7/8/2007 4:59:57 PM)
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Interesting question, and one that I doubt anyone has a simple answer to. Myself, if I were teaching your hypothetical class, I would take it in steps. First, I'd try to give them some scale of the solar system. I'd put various scaled pins into a circle of foam, about the size of a dinner plate...
"Okay, this represents our solar system. It's approcimately nine light hours across, not counting the Oort Cloud at the outer fringes. Imagine about three inches beyond this a tiny dot that represents Voyager II, the fastest moving man-made object. It was sent on a mission to Jupiter starting in the year 1978, about a year after Star Wars first came out, and Jimmy Carter was still in office. At this scale, the next solar system you might encounter would be Proxima Centuri, 4.3 light years away... that would make it about the same diastance here as New York to to LA."
Next, I'd replace the circle of foam with a smaller block, with only two pins in it, about six inches apart.
"This is our sun, and Proxima Centuri. At this scale, the center of the Milky Way, our home galaxy, would be about 50 miles away. (Insert the name of an appropriate city near you)"
Then, I'd replace the foam blocks with one of those large, swirled looking toy balls you can get from Wal Mart. On it, using a Sharpie pen, I'd place randomly little "@" symbols representing about 30 galaxies.
This would represent the "local group" of galaxies. There are about 30 of them, and the distance to them is varied, but they are all flying away from each other as space itself is expanding. So fast, that astronomers can actually measure the "red shift" in their light as they do so.
Beyond this, we deal in specualtion. Thanks to dark feild astronomy (pointing telescopes into areas of space where there are no visible stars, and taking extremely long exposures) We know there seem to be BILLIONS of galaxies out there, each localized group of galaxies (like our own local group of about 30) would be represented by a single grain of salt. Now, salt the parking lot of the local mall on a snowy day... and you've got an inkling of the scale of the known universes.
Problem is, we don't know if this is the only one.
If you have access to a copy of "Cosmos" the old Carl Sagan series on PBS, you could play the first half of episode #1, where Carl takes us through a half hour long explanation of this very topic. The boxed set is about $100, and worth every penny, even if a few of the episodes are beginning to date themselves... (mostly because we've found out so much more about the outer soloar system in the last 25 years.)
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