Illusions hold a very special place for almost everyone.
If you have ever gone to a science center which has a display of optical illusions, you might have watched people spending large amounts of time staring at and attempting to understand why they were perceiving the illusions that they were. One optical illusion that holds an interest for me is the kind that uses background objects, lines, or other features to alter the appearance of foreground objects. If you don't believe that the lines are truly straight, turn this page edgewise and look down on them. There is one special illusion that has held my interest since childhood, and that is the illusion of the apparent increased size of the moon when seen near the horizon. When the full moon is rising or setting, it appears larger than it does when viewed much higher in the sky.