# The Interesting Moon

I’ve become interested in the moon. I like to watch the moon and it’s night-to-night (day-to-day) changes and learn new things about the moon phases.  (It is all very logical and there is a lot of symmetry.)

Here are a few useful facts for moon watching:

• The definition of a full moon is that it is on the opposite side of the earth as the sun. Therefore, moon rise = sunset. Usually there is not an eclipse, but when there is, it is near a full moon.
• The definition of a new moon (it’s blank, can’t see it) is that it is on the same side of the earth as the sun. Therefore, moon rise = sun rise. The sun is shining on the other side of the moon.
• The ‘full moon’ is a date and time of day (and days start at 12:00 midnight). Therefore, if we look at the moon before midnight, the moon may appear more full the day before a full moon than on the actual evening of the full moon. I’ll let you look at this table, and see if you can explain why this is true.
• Prior to a full moon:
• The moon rises before sunset. This makes it easy to predict that a full moon is coming.
• The moon is unfull on the left side. (Why?)
• After a full moon:
• The moon rises after sunset.
• The moon is unfull on the right side. (Why?)
• There are 29.5 day’s between new (or full) moons (in a moon cycle). The moon cycle begins with, you guessed it, the new moon.
• 2 full moons can happen in one month, but it’s rather rare. Therefore, it is called a Blue Moon.
• Q: What is the change in the moon rise from one day to the next? A0: Well, that depends. (I hate that answer!) A1: The average change in the moon rise from one day to the next is 49 minutes, which is 24 hours ÷ 29.5.  A2: The change in the moon rise from one day to the next ranges from around 79 minutes (near the full moon) down to around 23 minutes (near the new moon). A3: The change in the moon rise from one day to the next ranges from about 25 minutes to about 75 minutes, with an average of 50 min.
• The First (and Last) Quarter moon appears as half a moon. This is one-quarter and three-quarters of the way through the moon cycle. The full moon being half way through (well, tw0-quarters, but no one wants tw0-quarters). Q: Which half shows on the first and last quarters?