Is it a coincidence that the Sun and the Moon look of same size from the Earth?

(astronomy.stackexchange.com)

15 points | by melenaboija 17 hours ago ago

2 comments

  • olyjohn 11 hours ago ago

    Do they really look the same size? The moon itself doesn't even look the same size consistently. Some nights it looks gigantic. I can't even look at the sun long enough to tell what the definitive size of it is.

    • gregw2 4 hours ago ago

      The conclusion that the sun and moon look the same size in the sky is most intuitive when you think about how ecipses appear to us. The relative curve shapes when the moon covers the sun, and the ways total eclipses appear to match sizes do suggest they do "look" the same size to earth observers.

      Regarding seeing gigantic moons, I know what you mean. There is a weird psychological effect where objects, particularly the moon, look bigger near the horizon than at the top of the sky that is apparently in our heads and not due to any physics of, say, refraction. I've tested this for myself by pinching a large moon between my fingers and watched it visually then suddenly seem much smaller.