The Primal Moon

      As February rolls into March the moon is marching towards full again. The slender crescent appearing in the western sky at sunset will rise earlier each day until on March 9th when it rises full in the east at sunset. This cycle has been going on for eons and has been am important part of nearly every culture on Earth. But did you know that the early moon was much different than the one we see today?

     To us, the full moon is certainly the brightest thing in the night sky. It cast enough light to read by and to cast deep shadows. Even in the city it is hard to not notice the full moon. But our full moon of today is little more than a dim lightbulb when it is compared to full moon of primal earth. The earliest full moons would dazzle the eye!
 
      In its present orbit, the moon is approximately 240,000 miles from earth. We can easily cover up the moon with a thumb held at arm's length. But the primal moon was a different story altogether. It's orbit was a mere forty thousand miles from Earth: about one sixth the present distance.!  Such distances however, are hard to imagine. It is a bit easier to grasp this fact when you realize how much larger the full moon would have looked at this closer distance. In short, it would have been enormous, almost forty times larger than our full moon of today.  And there would have been other changes in the primal lunar show.

      In addition to distance and apparent size, the moon would been a speed demon in our night sky. Today, it takes the moon almost a month to complete one orbit around the earth. But the primal moon would have taken a mere forty-eight hours to make the same trip! In fact, the moon moved across the sky so fast that had humans been there to see the moon, we would have been able to detect changes in the phases of the moon during a single night.  This is even more remarkable when you learn that the earth's day was only ten hours rather than twenty four!

      One thing which has not changed is the way in which the moon and earth rotate with respect to each other. Since gravity first attracted the two together, they have been locked in an unchanging embrace. With the same side of the moon always facing the Earth.

      The gravitational pull between the two bodies has however slowed the Earth's rotation, and will continue to do so. This is why we now have a twenty-four hour day and why those folks who wish for more hours in a day will someday get their wish! These same forces also act on the Moon, causing the distance between earth and Moon to increase by about 1.5 inches (3.81cm) a year. Eventually very far into the future, the moon will escape the gravitational bonds of earth and be a free moving object. If we could go forward in time to witness this event it would likely be a sad one. Gone would be our nearest neighbor in space, the world where humans  took their first tentative footsteps in our journey into space.