The moon Essay: In the course of a single day, it causes the ocean’s tides to rise and fall dramatically. It also slows down Earth’s rotation slightly, lengthening the length of our days by about 2,000 milliseconds every century.
The Moon is a type of natural satellite in space, and it has been the subject of human interest throughout history. The Moon is one of the largest natural satellites in our solar system.
It has a diameter about one-quarter that of Earth’s, and it’s the second-densest satellite after Jupiter’s moon Io. In addition to its size, the Moon is notable for being the only extraterrestrial body that humans have set foot upon thus far .
The Moon Essay
This large mass orbiting our planet exerts a powerful gravitational pull on Earth and all things situated on its surface or near it. The gravitational attraction is the force working between any two celestial bodies that tries to bring them closer to each other.
As a result of this tide-raising force, the water level on Earth’s surface rises and falls by about 1 meter (3 feet), twice daily – once during the Moon’s transit over the local meridian and again when it crosses the antipodal point.
By contrast, the solar tides caused by Earth’s rotation around its axis are much smaller since they depend on our oceans’ response to Earth’s daily rotation with respect to the Sun.
This phenomenon isn’t limited to those parts of Earth where all or part of the ocean happens to be facing towards and away from the Moon: as seen from any point on the globe, both the Moon and the Sun together can be observed to exert a tide-raising force. In fact, the solar portion of this effect is roughly ten times stronger than that of the Moon alone.
The gravity field created by the Moon varies from place to place around Earth. Such variation in gravitational strength across our planet is much smaller when it comes to any other celestial body. As a result, objects at or near sea level are subject to a noticeable difference in gravitational pull depending on where they’re located with respect to the Moon’s position in space – which happens to vary as it orbits Earth every month.
When an object moves closer to another massive object such as the Earth, its potential energy decreases because its gravitational potential energy increases. A higher gravitational potential means a more negative gravitational potential – the strength of the gravitational field is greater – and, hence, a stronger pull of gravity.
The Moon appears to be moving around Earth because, from our perspective here on Earth’s surface, it appears to circle around our planet once every 28 days . In reality, however, the Moon orbits Earth about once every 27.3 days , or roughly once a month. As the Moon makes its monthly journey around us , we always see exactly half of it – that is why we say that we see one side of the Moon .
At any given moment as it orbits Earth, we see only one hemisphere of the Moon: half of its disc is illuminated by the Sun, thanks to the Moon’s synchronous rotation with Earth (more on this later) – or, simply put, it always presents the same side to us.
The time it takes for the Moon to rotate once on its axis is the same as the length of its orbital period around our planet: 27.3 days. If you were standing at one of Earth’s poles during first quarter phase , then within an hour and a half after first quarter phase began, you would see first quarter phase end ; that is how quick it is!
And if you could see far enough around the back side of the moon, you would observe another first quarter emerge after three days of darkness. This phenomenon would repeat every 29.5 days , the time it takes the Moon to rotate once on its axis and orbit Earth, because this is how long it takes for a lunar month.
The Moon undergoes phases just as the sun does, only at different times of the day rather than over longer periods of time. This happens because when our planet revolves around the Sun, it also simultaneously turns on its own axis . Since our night half faces away from the Sun half of each month, while we’re moving in our orbit around the Sun , one-half of that sphere – our daytime side – always faces towards it , giving us daytime during one-half of each orbital period .
On Earth’s nighttime side (in what is known as Eastern Standard Time or EST), the Sun is always located somewhere beneath the horizon . In the hours before sunrise , as viewed from any location at or near EST, the Moon appears beyond our planet’s nighttime side.
Soon thereafter, the Moon enters into a new phase as it emerges from our planet’s shadow and begins to shine by reflected sunlight. If you were standing on Earth’s night side during first quarter phase , you would see the waxing gibbous emerge above your eastern horizon around 1:45 am local standard time (LST) . It takes about an hour for the moon to shift its position in the sky so that it reaches its highest point above your horizon – this marks first quarter phase .
For observers positioned on Earth’s day side, separated by 180 degrees of longitude , the Moon appears high in the night sky at first quarter phase since it is located on the 180 degrees meridian , directly opposite the Sun.
As the Moon continues on its monthly journey around us, it keeps changing phases because our planet’s daytime side changes with time . At third quarter phase , which occurs 15-21 days after first quarter phase , our nighttime side faces away from the Sun once more, so we experience another period of darkness. This marks second quarter phase for those who are awake to witness it.
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