The sun and the moon are ten miles away

The sun is 100,000,000 miles away, 1,000,000 miles across, whereas the moon is 100,000 miles away, 1000 miles across.  (All numbers are rounded to the nearest power of 10.) Our eyes miss these vast scales entirely and see both objects as of comparable size and distance, much closer than they really are. They seem, what, maybe 10 miles away and 1/10 mile across?

I’ve long been interested in what I call “the other moon illusion”: if you consider the sun and moon together in the sky, you will judge, the moon should look fuller!  This illusion results from failure to perceive that the sun is further away than the moon.  It amuses me to note that to eliminate it, we wouldn’t have to perceive the truth, that the sun is a thousand times further than the moon, let alone that it is ten million times further than it looks.  If we could only perceive it as 20 miles away instead of 10, that would be enough.

[7 January 2016]

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