The Phases of the Moon
To behold the wandering Moon,
Riding near her highest noon,
Like one that has been led astray
Through the heav'n's wide pathless way.
-John Milton (1608-1674)

Also visit: Moon Phases Calendar to find out what the moon will look like night-by-night.
Here is a really neat animation of the moon through an entire lunar cycle (from Astronomy Picture of the Day). Also, I have a page of Lunar Eclipse pictures I took in March 1997.
(Links to sites with more Earth, Moon and Planet's Info)

The light part of the circle represents the side of the moon that is illuminated by sunlight, whereas the black part represents the side that is in shadow.

As seen from space...

Space View

This diagram represents the Moon's orbit around the Earth as seen from a location in space above the Earth's North Pole (it is NOT drawn to scale) - the Earth is also colored to indicate day and night. The moon orbits in a counter-clockwise sense in this diagram with the side facing the Sun always being illuminated. From Earth we see different amounts of the lit side depending on where the Moon is in its orbit. It is interesting to notice that during the phases from just after Third Quarter to just before First Quarter the Moon is located on the day side of Earth - or in other words it can be seen during the day at the same time as the Sun.

As seen from Earth...

New Moon Located in the sky near the sun, can't be seen (except for solar eclipses).	Waxing Crescent Best seen in the Western sky around sunset. Can be seen during the day to the East of the Sun.	First Quarter Can be seen high in the South, in the evening.
Waxing Gibbous Can be seen in the Eastern sky in the evening.	Full Moon Rises about the same time the sun sets. Can be seen late in the evening to midnight in the East.	Waning Gibbous Rises after midnight. Best seen in the middle of the night or early morning.
Third Quarter Can be seen high in the South, in the morning before sunrise.	Waning Crescent Best seen in the Eastern sky right before sunrise. Can be seen during the day to the West of the Sun.	New Moon

Try this!

Here is a simple activity you can try to demonstrate why the moon appears to go through phases as seen from earth.

What you will need:

A small styrofoam ball about 5cm (2 inches) in diameter (actually any small ball, like a golf ball, will work, it's just easier with a styrofoam ball)
A bright light like a lamp (with the lamp shade removed), overhead projector, or slide projector (with a clear slide, or no slide in it)
A pencil
A dark room

The idea:

Your head will represent the Earth (the top of your head will be the North Pole, under your chin will be the South Pole, your nose will be on the Equator), the light will be the Sun, and the small ball will be the Moon. You are going to follow the Moon through one complete "orbit" to see how the patterns of light and dark change on the Moon.

What to do:

Setup the light in a darkened room so the bulb is at about the hight of your shoulders (actually, setup the light with the lights in the room on, then turn the room lights off when you are ready to begin the experiment).
Stand about 5 feet away from the light (so the light shines on you), face the light.
Stick the styrofoam ball on the end of the pencil (so it looks like a lolly-pop --- if you don't have a styrofoam ball, just hold the ball you do have between your index finger and thumb, start with it in your left hand, make sure your fingers don't block the ball or the light).
Hold the pencil with the ball on the end of it (or the ball between your index finger and thumb) out at arm's length in front of you.
Start with the Moon (ball) between you and the Sun (light), this represents New Moon, the whole Moon looks dark (and you probably will have trouble seeing it because of the light).
Then "orbit" the Moon (ball) to your left by turning your body while staying in the same spot. As you turn watch how the pattern of light and dark on the ball changes.
When you are turned so your right shoulder is closest to the light, half of the Moon will be lit up, this represents First Quarter.
When you are turned so your back is to the light (you may need to lift the ball up higher to get it out of the shadow of your head), you will be at Full Moon and the whole side of the ball you can see will be lit up.
Once you are at Full Moon, you may need to switch the ball to your other hand before continuing (so your hand doesn't block the light).
Keep turning to your left, once you reach the point where your left shoulder is closest to the light, you will be at Third Quarter and again only half of the Moon will be lit up (but this time the opposite half than what you saw at First Quarter will be lit).
Continuing to turn to the left, you will eventually return back to New Moon and can start the phases all over again.
It takes the moon about a month to go through one complete cycle of the phases.

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