A Little Lunar Physics

With my celestial gazing blotted out by the grey weather again last night, I turn to a bit of chat about astronomical angles with some solar/lunar synchronicity tossed in for leavening. As I am sure most of you know, but may not often contemplate, the moon has no light of its own. Earth's satellite is a reflective surface, what we see as the illuminated moon is completely solar energy cast back at us.

So when we see or don't see the new moon, it is because the moon is between the earth and the sun. All the light of the sun is on the far side of the moon, which contrary to what Pink Floyd is thought to have said, is not the dark side of the moon at all. At the other apex of earth/sun/moon alignment, a full moon occurs when the earth is between the sun and the moon with the full illumination of the sun on the earth facing moon countenance. The graphic below illustrates these facts of celestial physics. 

When the earth lines up exactly between the sun and the moon, we get a lunar eclipse and I would be remise if I did not remind you that this year on the winter solstice (Dec. 21st) there will be a total lunar eclipse visible in most of North America.

There is no dark side of the moon really. Matter of fact it's all dark.

Pink Floyd Eclipse from Dark Side of the Moon