Can the sun be different sizes?

A recent question from a viewer is related to the sun's size, and could it possibly change sizes throughout the day:

Question: Why does the sun appear so much larger in the morning when it rises than in the middle of the day, and then gets large again when it sets? Could it change size during the day?

A: This apparent change in size of the sun and the moon is merely an illusion. While there are numerous competing theories to explain this illusion, most involve optical processes of viewing distant objects.

One way to convince yourself that the apparent change in size is merely an illusion is to do the famous finger test. Use the moon because it's dangerous to look directly at the sun. Just extend your arm and compare the size of the moon at its zenith (the highest peak) to a finger or thumbnail. Do the same when the moon is at the horizon. The moon will be the same size.

It's amazing how optics can fool you. In fact, I'm still searching to find the end of the rainbow to claim my pot of gold. :)~

For an interactive look at the sun go to this link: http://www.spaceweathercenter.org/SWOP/Interactives/1.html