Sunday, April 29, 2012

It's A Long Way to Tipperary -- And More Than A Billion Times Farther to Alpha Centauri

There was a question to my first post regarding the distance between stars.  I'll try to answer that now.

I think that the problem is that people build up the scale something like this.  A plane flight from New York to Los Angeles (or something similar) is probably about the longest single trip they've taken.  They know the distance from earth to the moon is a lot farther than that, so they think, "OK, multiply by 20."  They know Mars is a lot farther away than the moon, so they multiply by 20 again.  They know the nearest star (not the sun) is a lot farther away than Mars, so they multiply by 20 one last time. I'm not saying they do this on purpose; it's just that this is about as good as the human imagination (as opposed to human mathematical reasoning) can do. If we take the New York to California distance to be 3000 miles (it's just a little less), we end up with a distance to the nearest star of about 24 million miles in our imagination.  That's less than the real-world distance to Mars when it's closest to earth. The real distance to Alpha Centauri (a little farther than the dwarf Proxima Centauri) is one million times farther away.

In order to do justice to what a distance like that means in practical terms, I'll have to figure out a way to include equations in this blog posting.  I'll get back to that later this week.

Update:  So much for "later this week."  Well, at least I did get around to it eventually.

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