No, I'm not counting down that accurately! That's the average length of one moon cycle.
The revolution of the Moon around the Earth makes the Moon appear as if it is changing shape in the sky. This is caused by the different angles from which we see the bright part of the Moon's surface. These are called "phases" of the Moon. Of course, the Moon doesn't generate any light itself; it just reflects the light of the Sun. The Moon passes through four major shapes during a cycle that repeats itself every 29.5 days. The phases always follow one another in the same order. What you see when you look at the moon depends on its location in relationship to the sun and Earth. We see a different fraction of sunlight being reflected from the moon to Earth. (Lifted from this website.)Whenever I'm trying to figure out whether the moon is waxing or waning, I remember the lyrics to Becky Reardon's song (which is a lovely, but tricky, round):
Where is the Moon when the Moon is new?We've all heard stories about the moon's effect on everything from accidents to lovesickness to werewolves. Did you know there are some serious studies that measure the effect of lunar cycles on the Dow Jones Industrial average? Good time to study up on it. One theory, proposed in the 1930s was that wheat should be bought on a full moon and sold on a new moon (I thought that was for planting, not buying and selling). A study in 1994 noted a correlation between the lunar cycle and Federal Reserve actions. Wow, the moon must be spinning like a top this week!
It’s a sliver on the right growing bigger every night.
Where is the Moon when the Moon is round?
Rising when the Sun is going down.
Where is the Moon when the Moon is waning?
Fading to the left ‘till there’s no Moon remaining.
"This graph reveals that the DJIA has, on average, risen from the new moon for about 7 days. The DJIA then has bottomed about 4 days before the next new moon. The price slide seems to accelerate after the occurrence of the full moon." (I know, I can't read it either, you'll just have to trust it. Wait -- where have I heard that before?)