Phases of the Moon By Moira Whitehouse PhD

If you look at the sky, you will notice the shape of the Moon changes each night. These different views are called the phases of the Moon.

What causes the Moon's phases? The Moon goes through phases (the view seen from Earth at various times in the Moon cycle) because: the Moon is revolving around the Earth, 2) the Moon is reflecting sunlight towards the Earth.   

Interestingly, the same half of the Moon is always in sunlight, and the other half if it is always dark.  (now think about that) For this reason, we can see only the portion that is lit, which, depending on its position in the orbit, usually gives us a view of only part of the Moon.

Although it is really a continuous and gradual change, there are eight recognized phases that the Moon goes through and they always occur in the same order.  In this repeating pattern the Sun's reflected light moves across the surface of the Moon, in our view, from right to left. 

The Moon changing phases quickly over 28 days (about a month).

The phases of the Moon are:

As shown in the diagram, the new moon occurs when the Moon is positioned between the Earth and Sun. The entire illuminated (lit up) side of The Moon is on the back part of the Moon– the half that we cannot see. http://www.wisegorilla.com free clip art for educational use

The first quarter and third quarter moons (both often called a "half moon"), occur when the Moon is at a 90 degree angle with respect to the Earth and Sun. So we are seeing exactly half of the Moon illuminated and half in shadow. http://www.wisegorilla.com free clip art for educational use

At a full moon, the Earth, Moon, and Sun are approximately lined up, just as they are in the new moon, but this time the Moon is on the opposite side of the Earth. As a result, the entire sunlit part of the Moon is facing us. The shadowed portion is entirely hidden from view. http://www.wisegorilla.com free clip art for educational use

The first quarter and third quarter moons (both often called a "half moon"), occur when the Moon is at a 90 degree angle with respect to the Earth and Sun. So we are seeing exactly half of the Moon illuminated and half in shadow. http://www.wisegorilla.com free clip art for educational use

Although we give names to certain phases, each night the change is actually gradual.

Review: •Remember we give names to the various phases of the Moon as seen from Earth, but the rotation is continuous us, it never stops at any phase. : •The gravity of the Moon’s huge mass affects our oceans causing them to bulge toward the Moon, causing the tides.