Re: Why does the Sun appear bigger some days?

The Sun does look bigger on some days than others, but this is not because it is closer than usual. We would indeed burn up if it came a lot closer than it is, and freeze if it moved away.

The reason the Sun (and the Moon) sometimes looks like it has a different size probably has to do with where you see it in the sky. If the Sun is near the horizon, it may often look bigger than when it is right overhead. The Sun's disk is also easier to see when it is not so bright---for example, when it is near the horizon and therefore you may look more at it and wonder about its size than when it is overhead and is uncomfortably bright.

NEVER look directly at the Sun! It can destroy your vision. However, on some days when the Sun is behind thin clouds, or when the Sun is near the horizon, one might catch a glimpse of the Sun's disk.

Why exactly something should look bigger when it is near the horizon is apparently has no good explanation, but it may have something to do with being able to compare things to each other---the horizon may provide houses and trees and mountains to see the Sun and the Moon along side of. Right overhead you will most likely only see the Sun and there is nothing to compare with.

There is a book that tells you more about this, that you might be able to get your school library to get for you. It is called The Nature of Color and Light in the Open Air and is written by Minnaert. It is published by Dover Books a long time ago, but is so good that I think you can still get it through a library. In that book you should be able to read up on more ideas about why the Sun (and the Moon) sometimes looks bigger than otherwise.

Remember: NEVER look directly at the Sun.

[Moderator: You may want to demonstrate to yourself that the size of the Sun or Moon really is an optical illusion. The best way to do this is to use the Moon. Some night when it is on the horizon, measure its size. For instance, find a coin that when held at arm's length the coin just covers the Moon. Repeat this measurement about six hours later when the Moon is overhead. You'll find that the coin still just covers the Moon. The actual angular size of the Moon has not changed, but its apparent size certainly has. An optical illusion.]