2The lunar month is the 28 days it takes to go from one new moon to the next. During the lunar month, the Moon goes through all its phases.
3We only see the Moon because sunlight reflects back to us from its surface.
4During the course of a month, the Moon circles once around the Earth During the course of a month, the Moon circles once around the Earth. If we could magically look down on our solar system, we would see that the half of the Moon facing the Sun is always lit. But the lit side does not always face the Earth!
5As the Moon circles the Earth, the amount of the lit side we see changes. These changes are known as the phases of the Moon and it repeats in a certain way over and over.
6Moon Phase Descriptions... Although this cycle is a continuous process, there are eight distinct stages, called phases. These phases of the Moon, in the sequence of their occurrence (starting from New Moon), are shown below.
7New Moon - The Moon's dark side is facing the Earth New Moon - The Moon's dark side is facing the Earth. The Moon is not visible. The lighted side of the Moon faces away from the Earth. This means that the Sun, Earth, and Moon are almost in a straight line, with the Moon in between the Sun and the Earth. The Moon that we see looks very dark.
8Waxing Crescent Moon - As the Moon moves around the Earth, we get to see more and more of the illuminated half, and we say the Moon is waxing. At first we get a sliver of it, which grows as days go by. This phase is called the crescent moon.
9Quarter Moon - A week after the new moon, when the Moon has completed about a quarter of its turn around the Earth, we can see half of the illuminated part; that is, a quarter of the Moon. This is the first quarter phase.
10Waxing Gibbous - The Moon appears to be more than one-half but not fully illuminated by direct sunlight. The fraction of the Moon's disk that is illuminated is increasing. This Moon can be seen after the First Quarter Moon, but before the Full Moon. The amount of the Moon that we can see will grow larger and larger every day. ("Waxing" means increasing, or growing larger.)
11Full Moon - The Moon's illuminated side is facing the Earth Full Moon - The Moon's illuminated side is facing the Earth. The Moon appears to be completely illuminated by direct sunlight. The lighted side of the Moon faces the Earth. This means that the Earth, Sun, and Moon are nearly in a straight line, with the Earth in the middle. The Moon that we see is very bright from the sunlight reflecting off it.
12Waning Gibbous Moon - From now on, until it becomes new again, the illuminated part of the Moon that we can see decreases, and we say it's waning. The first week after full, it is called waning gibbous. The amount of the Moon that we can see will grow smaller and smaller every day. ("Waning" means decreasing, or growing smaller.)
13Last Quarter - One-half of the Moon appears to be illuminated by direct sunlight. The fraction of the Moon's disk that is illuminated is decreasing. Sometimes called Third Quarter. The left half of the Moon appears lighted, and the right side of the Moon appears dark. During the time between the Full Moon and the Last Quarter Moon, the part of the Moon that appears lighted gets smaller and smaller every day. It will continue to shrink until the New Moon.
14Waning Crescent - The Moon appears to be partly but less than one-half illuminated by direct sunlight. The fraction of the Moon's disk that is illuminated is decreasing. This Moon can be seen after the Last Quarter Moon and before the New Moon. The crescent will grow smaller and smaller every day, until the Moon looks like the New Moon.
15A while after four weeks the illuminated half of the Moon again faces away from us, and we come back to the beginning of the cycle: a new moon.
16Moon Phase Misconception... "The most common incorrect reason given for the cause of the Moon's phases is that we are seeing the shadow of the Earth on the Moon! But this cannot be correct: when the Moon passes through the shadow of the Earth, we get a lunar eclipse. Anyone who has seen a lunar eclipse, though, might remember that the Moon actually passes through the Earth's shadow only rarely, so that can't be why the Moon has phases. The real reason for the Moon's phases depends on two things: the Moon is round, and the angle it makes with the Earth and Sun changes over its orbit." - As Quoted From Bad Astronomy