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.

Let’s look at the phases of the Moon on a calendar for February, 2013. Notice that the change from phase to phase is very gradual and takes about a month for the whole cycle.

http://www.moonconnection.com/moon-february-2013.phtml

2) the Moon is reflecting sunlight towards the Earth.

What causes the Moon's phases?

The Moon goes through phases (the view seen from Earth at various times in the Moon cycle) because:

1) the Moon is revolving around the Earth,

Interestingly, the same half of the Moon is always in sunlight,

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.

(now think about that) and the other half if it is always dark.

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 andhalf 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 portionis 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 andhalf 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.

http://www.valdosta.edu/~cbarnbau/astro_demos/frameset_moon.html

Select Moon Phases in the following URL for an outstanding animation of the Moon and its phases.

Select “Moon Phases”

http://astro.unl.edu/naap/lps/animations/lps.html

The gravitational pull of the Moon, though less than that of the Earth, is strong enough to causes water in the oceans to shift slightly toward the moon as it passes overhead. This is seen as a rise or fall along the oceans shores that we call the tide.

Tides

When the water level is the highest it is called high tide. When it is the lowest it is called low tide.

The level water on the beaches around the world rise and fall every twelve hours.

high tide low tide

low tide

high tide

: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.