• Question: why is there a full moon only once a month

    Asked by to Juan, Joe, Kate, Rory, Rosie on 18 Mar 2014. This question was also asked by .
    • Photo: Rosie Coates

      Rosie Coates answered on 18 Mar 2014:

      The lunar phases occur because the moon orbits the earth about every 29.5 days. If you think about yourself as the earth. Everyone living on your back would have night time when the sun was in front of you. The people on your back only see a full moon when the moon is behind you and the sun is in front of you and all three are almost in a straight line so the whole of the moon is illuminated by the sun.

      I say almost a straight line because a perfect straight line would mean that there would be a lunar eclipse that would stop sunlight hitting the surface of the moon. The only light hitting the moon is the sun’s light reflected from the earths atmosphere. This usually causes the moon to appear a copper red colour.

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