Weather Blog

Does the full moon really appear larger near the horizon?

Does the full moon really appear larger near the horizon?
Photo of moon rising behind Cascade Mountains from Richmond Beach, Jan. 19, 2011. (Photo: Joe Michael)

After a beautiful sunset Wednesday evening, the full moon rose to a stunning display across the Puget Sound area.

Many people remarked that the moon looked huge -- much larger than it usually does when it's high in the sky. But then again, full moons seem to frequently appear large near the horizon.

Is there some sort of atmospheric trick in play? Or is it just your mind playing tricks on you?

I always thought it was some sort of atmospheric effect where the air bends the light waves to make it appear larger. But the fascinating part is, if you take a picture with your camera, the moon comes out looking normal. Or, does it?

In this photo of a moon rising over Seattle, the camera shows what your mind doesn't see -- the moon stays the same size, although I'm sure to the photographer, the moon probably looked huge when it was near the horizon and skyline.

But then again, look at this other photo taken Wednesday night by Joe Michael of the moon rising over Richmond Beach.

See, even there it looks larger than usual to me. Hmmm....

This might be akin to this brain teaser I featured in my blog a little over a year ago:

The question is: Are the squares marked "A" and "B" the same color?

Surely, they are not. But actually, they are. Those of you who are Photoshop savvy can copy the image off this web site and see for yourself.

And if you want to see the explanation behind it, here is the original site by the MIT professor who created it.

Back to the moon, scientists have long sought to explain the optical illusion but there is still debate over which explanation is correct.

Here is the original thinking: http://unmuseum.mus.pa.us/exmoon.htm.

But here is a newer explanation that's surfaced over the past few years.

Either way, it sure looks spooky!