09 March 2009

The Stars, So Far Away

Interesting facts about astronomical scales.
  • If the moon were a ping pong ball, the Earth would be a softball, and the ping pong ball moon would be a shade under ten feet away.
  • If the Earth were a pea, the Sun would be a sphere about a yard in diameter, about 3/4 length of a football field distant (75 yards).
  • Skipping the next scale up (best for last): If the model Sun is an infinitesimal mote one inch from the next nearest star (the distance to which is very roughly the typical distance between stars in the disk of the Galaxy), then the model Galaxy will be about four tenths of a mile in diameter.
  • If the model Galaxy is a 12 inch dinner plate, the next comparable big spriral galaxy (M31 in Andromeda) is another plate, at a tilted angle, floating about 18 feet away.

All of these are within an easily grasped proportion of the size of the celestial object in relation to its distance from the next similar such object. But take the one I skipped: the average distance between stars. Let's take the Sun and the nearest comparable star, Alpha Centauri A, which is roughly similar in size to the Sun (it has companion stars, as do roughly half of all star systems, but we'll ignore that). This distance is about 4.3 light years, or 26 trillion miles.

If a model Sun (actually about 1 million miles in diameter), is a 1 foot sphere, a little bigger than a basketball, Alpha Centauri A will be a just slightly smaller sphere, but its distance would be about 4800 miles, roughly the distance from Denver to Paris.

All of which shows that in the various scales of the universe, the real 'hole,' where a (proportionally) huge void separates one thing from its like, is the distance between the stars.

This has all kinds of interesting implications for the origin of life, the formation and stability of planets and their orbits, the prospects for direct exploration of other star systems, etc. But for now, I leave it as an interesting factoid.

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