Moon Project

Lea Barcus

Astro 109

E. Enriquez

Mon. at 9:00 a.m

Moon Project

Over the month of November I took a photograph of the moon every night. While monitoring the moon I noticed that not only did the shape change from crescent to full moon, but the moons position in the sky changed as well. By the observations I took while watching the moon change phases I would assume a full cycle takes approximately 30 days. The different phases in this cycle, and the fact that we never see the "far side" of the moon are caused by the position and rotations of the earth, moon and sun. These rotations are also responsible for solar and lunar eclipses.

There are eight different phases in the moon's cycle and the moon changes it's shape during each one. The five shapes the moon can appear to be are called the new moon, crescent, half moon, gibbous, and full moon. When you look at my pictures, you notice that it takes approximately 4 days to switch from one shape to another. The first phase is a new moon; this is when the moon is not visible at all. About four days later the moon will be a waxing crescent, this means less then half of a circle is visible. This will change into the next phase, the first quarter, in which you see a half moon. The half moon will become a waxing gibbous where a little bit more then half the moon is visible before reaching the fifth stage, the full moon. Although my own observations only tracked the first five phases, to become a new moon again the next three phases would be waning gibbous (a little less then a full moon is visible), the last quarter (half the moon is visible), and waning crescent (less then half the moon is visible). Because my pictures show that it took approximately half a month to get through four phases you can assume that it would take an entire month (30 days) to get through all 8 (Col.)

The reason the moon goes through these phases has to do with the positions of the earth, moon, and sun. The sun only hits the moon from one direction and as a result the sun always illuminates half of the moon. The phases are created because the moon is rotating around the earth. When there is a new moon, the sun is covering the far side of the moon only and the part of the moon facing earth is in darkness. On the contrary, when there is a full moon the sunlight is fully covering the part of the moon that faces earth. When there is a half moon, only half of the side facing earth is lit so only half of it shows, even though half of the far side of the moon is lit as well (Seeds and Backman24.)

The next question that this brings up, is how come the same side of the moon always faces earth, how come one side is considered the far side? As I mentioned earlier, the moon