The Sun & The Moon

Posted by jns on 7 April 2006

I have a friend upon whom I can rely to send me, with some regularity, unbelievable photos and incredible stories, most of which turn out in the end to be fabricated photos and urban legends. Someplace in the forwarding of these things, someone will often add a wishy-washy “I don’t know if this is true, but….” and then carry on anyway.

Sure enough, the last photo I got from him was a beauty: an arctic landscape with a bright, tiny sun hovering on the horizon and, above it, an enormous crescent moon. It was quite a lovely image. The text with it said

This is the sunset at the North Pole with the moon at its closest point. And, you also see the sun below the moon. An amazing photo and not one easily duplicated. You may want to save this and pass on to others.

“…not easily duplicated” is correct! While the image is pretty, it’s a complete fabrication, and I’d like to think that should have been obvious to anyone seeing it. But then, I’d like to think a lot of things that turn out to have nothing to do with reality.

Happily, snopes.com says plainly that the photograph is a fabrication, created digitally by a German astrophysics student. (Follow the link for the details and to see the image.)

However, Snopes missed their chance to state the obvious: the photograph could not possibly be a real image of “sunset at the North Pole” for one simple reason that everyone should be able to spot — the image of the moon, compared to the image of the sun, is far, far too large.

But how could anyone be expected to know this^*, you ask? Well, I claim, nearly everyone knows the cause of total solar eclipses, even if they’ve never seen one: the moon passes between the Earth and the sun and exactly covers the disk of the sun for a short time.

The simple deduction, then, is that the apparent size of the moon, as seen from the Earth, is very nearly the same as the apparent size of the sun. Thus we know that this image, in which the moon is some 20 times the size of the sun, must be a fabrication.
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^* This is an interesting question, particularly since in films, night scenes are often created with a looming, full moon shot with a telephoto lens; the same is rarely done for the sun, unless it is near the horizon into which the movie’s heroes are riding. People often seem ready to accept that the apparent size of the moon is substantially larger than it is in reality, whereas they seem to imagine the apparent size of the sun to be rather smaller than it actually is. These mistaken notions are exploited in the north-pole “sunset” image.