Why is the moon bright and where does moonlight come from?

Why is the moon bright and where does moonlight come from?

The shape of the moon during the month, and seeing only one side of the moon, may lead you to Why is the moon bright and where does moonlight come from?. But the answer is not complicated either. The moon, unlike the sun, doesn’t generate its own light. Moonlight is actually sunlight that falls on the moon and bounces off it.

First, let’s make it clear that the Moon is the only natural “satellite” of the Earth. This means that it is a small body that revolves around the Earth, just as the Earth revolves around the Sun.

Why is the moon bright?

The only reason we can see the Moon from Earth, or see that it appears to be luminous, is because sunlight hits its surface and reflects off us. If you are wondering why the moon shines? It is simply that the moon shows its brightness on the side that faces the earth thanks to the sun. You were one of those who say that the moon shines, so know that this is not true. Why? Because the moon is a dark planet that does not radiate light, and what you see is a reflection of the sun’s light on the surface of the moon, add to that a very small percentage of the surrounding bodies.

The moon appears bright in the night sky primarily because it reflects sunlight. Here’s how it works:

1. Sunlight: The Moon has no light source of its own. It merely mirrors the sunlight it gets. When the Sun shines on the Moon, it illuminates its surface.
2. Surface reflectivity: The surface of the Moon is covered by a layer of fine dust and rocky material called regolith. This regolith reflects sunlight quite effectively. Some regions on the Moon are highly reflective, such as the lunar highlands, while others, such as the lunar maria (dark, flat plains), are less reflective.
3. No Atmosphere: Unlike Earth, there is no atmosphere on the Moon. Earth’s atmosphere scatters sunlight in all directions, which is why we see the blue sky during the day. On the Moon, there is no atmosphere to diffuse or absorb sunlight. This means that sunlight striking the Moon’s surface is not scattered away, instead being reflected directly into space and back towards Earth.
4. Distance: Compared to other celestial bodies, the Moon is relatively close to the Earth. Its distance varies, but on average, it is about 384,400 kilometers (238,855 mi) away. This proximity, combined with its reflective surface, makes it relatively bright in our night sky.
5. Phases: The moon goes through various phases during its orbit around Earth, from new moon (when it is not visible) to full moon (when it is fully illuminated). These phases are due to the changing angle between the Sun, Earth and Moon. When the Moon is in its full moon phase, it appears brightest because it is fully illuminated by the Sun.

Why can we see only one side of the moon?

Oddly enough, we can only see one side of the Moon from Earth. This is because the moon rotates on its axis in the same period of time that it takes to complete its journey around the Earth. Since the Moon has no atmosphere or air, direct sunlight for about fourteen days heats the Moon’s surface to a temperature higher than the boiling point of water. Meanwhile, the far side of the Moon is experiencing the coldness of a long, dark night.

We can see only one side of the Moon from Earth, a phenomenon known as “tidal locking”. This occurs because of the gravitational interplay between Earth and the Moon This is how it works:

1. Tidal Force: The gravitational force produced between the Earth and the Moon is known as the “tidal force”. These forces are strongest on the side of the Moon facing Earth and gradually decrease with distance.
2. Slow Rotation: Initially, the Moon rotated on its axis and showed different sides to the Earth as it rotated on its axis. However, the Earth’s gravitational pull on the near side of the Moon caused a sort of “bulge” due to tidal forces. This bulge caused the transfer of rotational energy to the Moon’s rotation in its orbital motion.
3. Tidal locking: Over billions of years, this transfer of energy caused the Moon’s rotation to slow until it reached a point where it became “tidally locked”. In other words, the Moon’s orbital period became equal to its orbital period. This means that the Moon takes about the same amount of time to rotate once on its axis as it does to revolve around the Earth. As a result, one side of the Moon is always facing Earth (the near side), while the other side (the far side) is permanently hidden from our view.
4. Far Side of the Moon: The far side of the Moon is not always dark; It gets as much sunlight as the near side. However, we cannot see it from Earth as it is always facing away from us. The only way to observe the far side is to send a spacecraft or satellite beyond the Moon and take pictures from there.

Read Also : How Different is the Soil of the Moon from the Earth?

The shape of the moon during the month

The shape of the moon is different every night we see it. We call it the “crescent moon” when we see a part of it illuminated, and the “full moon” when we see it completely round and illuminated, and “al-muhaq” when we do not see it at all. The phases of the moon are the phases that the moon goes through, and depend on the order in which the sun, moon and earth are located. In other words, the phases of the moon is the shape of the reflection of sunlight on the surface of the moon that we see.

For example, the moon is full when the Earth’s location is between the sun and the moon, and the moon is in full moon if the moon is between the earth and the sun, and it is an eclipse when the shadow of the earth’s shadow obscures the view of the moon completely.

We call this changing form of the Moon the phases of the Moon. The primary phases of the Moon are as follows:

1. New Moon: This is the beginning of the lunar cycle. During the new moon, the Earth-facing side of the Moon is not illuminated by the Sun, so it appears completely dark and is not visible in the night sky.
2. Waxing Crescent: Over the next few days, a small, curved sliver of the Moon will begin to appear in the western evening sky just after sunset. This is the waxing crescent phase. It is lit on the right and is in the shape of a thin crescent.
3. First quarter (half moon): About a week after the new moon, half of the moon is illuminated, and it resembles a half-circle or “D” shape. This is called the first quarter or half moon.
4. Waxing gibbous: In the days following first quarter, more of the Moon is illuminated, and it appears as a slowly increasing, but not yet completed, circle. This stage is known as waxing gibbous.
5. Full moon: About two weeks after the new moon, the full side of the Moon visible from Earth is illuminated by the Sun. This is the full moon phase, and it appears as a full circle in the night sky.
6. Waning Gibbous: After full moon, the illuminated part of the moon starts shrinking and it appears as a gradually decreasing circle. This is the waning gibbous phase.
7. Last quarter (half moon): About three weeks after the new moon, the other half of the moon becomes illuminated, forming another half moon. This is the last quarter.
8. Waning Crescent: In the last days of the lunar cycle, only a small, curved slice of the Moon is illuminated on the left. This is the waning crescent phase, which looks similar to the waxing crescent but is visible in the eastern morning sky just before sunrise.

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