Phases of the Moon

The 2011 Harvest Moon is next Monday, September 12. Will you be watching observing it?

What makes the moon cast its light in phases?

Here is a tasty way of demonstrating the process. Becky Nelson has a useful instruction sheet complete with oreo-template.doc.

Unlike the sun, the moon does not give off its own light; instead it reflects the sun’s light.  Because of the orbit of the moon, we don’t always see the whole moon illuminated. How much of the moon we see depends on the phase it is in. Over the course of a month, you can observe all the different phases. A great way to teach your children about this is to observe the moon every few nights and discuss which phase it is in. If you have binoculars or a telescope, be sure to use them in your observation! During the month, what other changes do you notice? Does the moon always appear to have the same color and size? Your kids might enjoy keeping a journal with sketches and observations of each stage.

There are eight main phases in the moon’s monthly cycle:

New Moon-the sun, moon, and earth are lined up, with the sun’s light reflecting off the side of the moon facing it. To the earth on the other side of it, the moon appears to be very dark at this stage.

Waxing Crescent-the stage between the new moon and first quarter; a sliver of brightness is visible on the right. The dark part of the moon is still what is most visible to Earth at this point.

First Quarter-the moon is to the left of the earth and sun (moving counter-clockwise); the sun’s rays shine on the half of the moon facing it, half of which is visible to Earth. Thus, it appears to be a “half moon,” half bright and half dark.

Waxing Gibbous-the stage between the first quarter and full moon, when most of the bright side is visible.

Full-the sun, earth, and moon are lined up, with the side of the moon facing the earth illuminated.
Waning Gibbous-occurs after the full moon; the right edge appears to be dark or invisible. The moon is in the position opposite where it is during its waxing gibbous stage.

Last (Third) Quarter-the moon is to the right of the earth and sun; because the sun’s light only falls on the side of the moon facing it, there also appears to be a “half moon” in this phase. The side that is bright is now opposite where it was during the first quarter, since the moon is on the other side of Earth.

Waning Crescent-occurs between the last quarter and the new moon; only a crescent of the bright side shows, on the left edge closest to the sun. The rest of the moon facing us is the “dark” side.

Moon in My Room is a classic tool for teaching the moon phases which has been popular for many years.