This shows the new moon phase of the lunar cycle as seen from Earth.
What is a new moon? The new moon is a phase of the lunar cycle the moon appears in about once a month. It is when we see the half of the moon that is not illuminated, due to the position of the moon, Earth and Sun. What we see from Earth is, well, total darkness. This is because we can't see any of the parts of the moon that are being illuminated by the Sun. This lesson will dive deeper into what the new moon phase is, when and how it occurs, and a few interesting lunar facts. Let's dive in!
What happens on a new moon is the moon is directly in between the Earth and Sun, when all three are in alignment. Is a new moon visible in the sky? It is not. The reason we can't see the new moon is because of our perspective from Earth. The side of the moon that is facing the Sun is lit up, and the side facing Earth is completely dark. Because the moon is visible only because of the sun's light illuminating it, and during a new moon none of the illuminated side is facing the Earth, the new moon phase appears invisible. Therefore, the new moon definition is as follows:
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Though the phases of the moon are not caused by Earth casting a shadow on the moon, the Earth and the moon do occasionally cast shadows on each other. When this happens, it is called an eclipse. There are two types of eclipses. One type is called a lunar eclipse, when Earth casts a shadow on the moon. The other type is called a solar eclipse, when the moon casts a shadow on the Earth.
A solar eclipse can only happen when the moon is in between the Earth and the Sun during the moon's new moon phase. During a solar eclipse, the moon passes in front of the Sun, blocking it out for a short period of time. So why doesn't this happen every time there's a new moon? The moon does not orbit Earth at 0 degrees; rather, there is about a 5 degree tilt to the moon's orbital plane. Because of this, sometimes the moon passes over the northern hemisphere, and at other times, it passes over the southern hemisphere. So most of the time, the moon does not align perfectly with the Earth and Sun for the moon to cast a shadow on Earth, causing an eclipse. In addition, the shadow the moon casts on Earth is very small (about 300 miles across). Therefore, in order to view a solar eclipse, one must be in the shadow that is cast. This makes actually seeing a solar eclipse when it occurs very difficult.
The new moon is one of the eight phases in the lunar cycle. The lunar cycle is the path the moon takes as it orbits, or moves around, the Earth. It takes about 28 days for the moon to orbit the Earth, or approximately one month, and it takes about 3.5 days for the moon to move from one phase to the next. Because the lunar cycle repeats every month, it is possible to predict which phase the moon will appear in next. The new moon happens when the moon is in between the Earth and the Sun. It comes 3.5 days after the waning crescent phase, and 3.5 days before the waxing crescent phase.
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The moon is only visible because it is being lit up by the Sun. A common misconception is that the moon looks different because the Earth is casting a shadow on the moon. This is not the cause of the lunar phases. As the moon orbits the Earth, there is one half of the moon that is always illuminated by the Sun. The moon looks different over the course of the lunar cycle because we see a gradual change in the amount of the moon's illuminated side as it moves around Earth.