Thursday, October 4, 2007


A friend pointed out in a comment on yesterday's journal entry that my understanding of the lunar cycle was completely off. He is quite correct. The shadow of the earth DOES NOT create the phases of the moon. The phases are created by the position of the moon relative to the earth as it revolves around the earth. Half of the moon's surface is lit by the sun and each day as the moon revolves a bit further around the earth we see the size of the illuminated surface change. This photo of the moon was taken by the spacecraft Galileo on December 7, 1992 on its trip to Jupiter. We thank NASA and the Jet Propulsion Lab for sharing this photo.

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