When the Moon is rising near the horizon, people often perceive it as being quite large. If you see this, hold up an index finger on your outstretched arm next to the Moon, and you’ll see that it’s only about half a degree in diameter. One evening my son came frantically to me, asking “Dad, Dad, what’s the perigee [closest approach to Earth] of the Moon’s orbit?” At first I scrambled to look up the answer; then I recalled that there was a full Moon out, and it was rising just about the time of sunset. I stopped and asked him, “Why do you want to know this obscure bit of information?” He told me that a friend had phoned him and told him that the Moon looked unusually large and figured it was much closer to the Earth. It just looked unusually large when juxtaposed against distant trees.
John Huth, "The Lost Art of Finding Our Way"
