The crescent Moon waxes, or appears to grow fatter, each night. When half of the Moon's disc is illuminated, we call it the first quarter moon. This name comes from the fact that the Moon is now one-quarter of the way through the lunar month. From Earth, we are now looking at the sunlit side of the Moon from off to the side. The Moon continues to wax. Once more than half of the disc is illuminated, it has a shape we call gibbous.
The gibbous moon appears to grow fatter each night until we see the full sunlit face of the Moon. We call this phase the full moon. It rises almost exactly as the Sun sets and sets just as the Sun rises the next day. The Moon has now completed one half of the lunar month. During the second half of the lunar month, the Moon grows thinner each night.
We call this waning. Its shape is still gibbous at this point, but grows a little thinner each night. As it reaches the three-quarter point in its month, the Moon once again shows us one side of its disc illuminated and the other side in darkness. However, the side that we saw dark at the first quarter phase is now the lit side. As it completes its journey and approaches new moon again, the Moon is a waning crescent. Want another description of why the Moon has phases? Why do we see these different phases of the Moon?
There are few different reasons why notice different phases of the Moon. Remember that the moon revolves around the Earth. As the moon goes around the Earth, half of the moon is always illuminated by the Sun. Meanwhile, the other half of the moon is always in darkness. Sometimes we see the parts being illuminated, and sometimes we do not. The moon looks bright because we see sunlight reflecting off of it. Depending on the position, we can only see fractions of the illuminated surface.
For instance, when the Moon is between the Earth and the Sun, the side of the moon facing Earth is not illuminated by the Sun. Therefore, to us humans on Earth, the moon is dark, and we call this a New Moon. Earth's shadow covers all or part of the lunar surface. Our Moon doesn't shine, it reflects. Just like daytime here on Earth, sunlight illuminates the Moon. When sunlight hits off the Moon's far side — the side we can't see without from Earth the aid of a spacecraft — it is called a new Moon.
The rest of the month we see parts of the daytime side of the Moon, or phases. These eight phases are, in order, new Moon , waxing crescent , first quarter , waxing gibbous , full Moon , waning gibbous , third quarter and waning crescent. The cycle repeats once a month every During a lunar eclipse, Earth comes between the Sun and the Moon, blocking the sunlight falling on the Moon.
During some stages of a lunar eclipse, the Moon can appear reddish. This is because the only remaining sunlight reaching the Moon at that point is from around the edges of the Earth, as seen from the Moon's surface. From there, an observer during an eclipse would see all Earth's sunrises and sunsets at once.
A lunar eclipse occurs when the Moon passes through the Earth's shadow, just as a solar eclipse occurs when part of the Earth passes through the Moon's shadow. The reason is that the Moon's orbit around the Earth is tilted relative to the Earth's orbit around the Sun.
Throughout the year, the Moon's orbital tilt remains fixed with respect to the stars, meaning that it changes with respect to the Sun. About twice a year, this puts the Moon in just the right position to pass through the Earth's shadow, causing a lunar eclipse. As the Moon passes into the central part of the Earth's shadow, called the umbra, it darkens dramatically.
Once it's entirely within the umbra, the Moon appears a dim red due to sunlight scattered through the Earth's atmosphere. In fact, if you watched the eclipse from the surface of the Moon, you'd see the Sun set behind the entire Earth, bathing you in a warm red glow.
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