Why Are There Seven Days in a Week?
Why Are There Seven Days in a Week?

Why Are There Seven Days in a Week?

Did you ever wonder why we have seven days in a week? As it turns out the seven day week is based on the moon and not the sun.

The cycle of the moon spans over a 29 day period. It’s broken into four, seven day periods with one extra day that marks the end of one cycle and the beginning of another, the New Moon. This Dark Moon is not visible because sunlight isn’t being reflected from the moon’s surface.

  • Day 1 – 7 | Waxing Crescent and on day 7 will reach the Half Moon phase.
  • Day 8 – 14 | The moon moves from the Half Moon to the Full Moon. We can see the entire illuminated portion of the moon.
  • Day 15 – 21 | It moves from the Full Moon to the Third Quarter also called a “Half Moon”. The illuminated part is the opposite of the First Quarter.
  • Day 22 – 28 | The moon enters its last Quarter and moves from the Half Moon to the New Moon.
  • Day 29 | Called the New Moon and the Moon is not visible for one night. It will start its cycle over again.

It is kind of funny that we use two systems to keep time. The first would be the obvious system, the Sun. We measure our seconds, minutes, hours, days, and years with the sun. The Moon to measure our weeks and months. We need a leap year every four years to adjust the calendar back into alignment with the Sun and Moon.

The Dread Pirate Dave

David is the Editor in Chief of Postcards From the Edge. I was born on a cold November morning on the showy plains of Colorado. Like my father, before me, I am an American Nomad.

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