Full and Half moon

[kermit911]

I noticed on day a few months ago that the moon and the sun were both visible. Now I know the moon gets its light from the sun. The reason we have half moon and so on is because of the earth blocking light from the sun. It's the earths shadow we see on the moon.

On this day I saw both the moon and the sun at the same time and it was a half moon. How could it be a half moon?

[Gef]

The moon's phases are not caused by the Earth's shadow but by the relative positions of Sun, Earth and moon.

The Earth's shadow causes lunar eclipses.

See here: http://en.wikipedia.org/wiki/Moon_phases

[mibn2cweus]

The half of the Moon facing the Sun is the part we on Earth see illuminated by the Sun. Although the Moon orbit�s the Earth monthly, the Moon usually slips by above or below the Earth�s shadow. Given the relative distance between the Earth and Moon it is a small wonder when the Moon actually passes directly through the Earth�s shadow during a Lunar eclipse.

An even rarer anomaly is when the Sun and Moon are both visible during a Lunar eclipse.

[brachiopod]

The simple way of thinking about it is to hold a ball (spherical object) at arm's length in one hand, and shine a torch onto it held at arm's length in the other.

From your eye's viewpoint, you will see a � or � 'moon', as the light from the torch illuminates, to some extent or other, just one side of the ball (from your viewpoint).

Now, as you bring your arm holding the torch around your body, you will see a greater percentage of the ball illuminated.
Keeping the torch well above your head, hold the torch behind you, and the ball directly in front of you. What you see now is a "full moon".

Note that your body shadow has nothing to do with it.