Moon

We explain everything about the Moon, its formation, movements, relief and other characteristics. In addition, its impact on the tides.

1. Moon

The Moon is the only natural satellite that revolves around the Earth at a distance of approximately 385 thousand kilometers. It is the fifth largest satellite in the Solar System.

It takes 28 Earth days to go around the planet (translation movement) and to rotate on its own axis (rotation movement) so you always see the same lunar face from Earth.

In 1609, the Italian Galileo Galilei (astronomer, philosopher, engineer, mathematician and physicist) built the first sixty magnification telescope , with which he discovered the mountains and craters of the Moon. In addition, he observed that the Milky Way was composed of stars and detected the four major satellites of Jupiter .

On July 20, 1969, American astronaut Neil Alden Armstrong was the first man to set foot on the Moon . So far, twelve humans have stepped on the lunar surface after several expeditions. In November 2009, the discovery of water on the Moon was formally announced , following an operation carried out by NASA.

2. Origin and formation of the Moon

There are several scientific theories that explain the possible origin of the Moon. The most recent theory is called “great impact theory” and postulates its formation four and a half million years ago, as the result of a great collision between Earth and Mars (when the protoplanets were in their formation phase).

From the fragments that broke off the shock, a celestial body formed in which its magma melted until it crystallized and gave rise to the lunar crust. The star maintained its orbit around the Earth and became its natural satellite.

Other theories formulated in previous years are:

• Of the binary creation. He argues that the Moon and Earth originated in parallel, and that the satellite was a consequence of small particles that merged over thousands of years.
• Of the capture. He maintains that the Moon was originally an independent planet that, due to the Earth’s orbit and gravitational force, remained as its satellite trapped in Earth’s orbit.
• Of fission. It maintains that the Moon was separated from the Earth while the latter was in the process of formation and gradually solidified until it became the natural satellite. This theory was discarded by the differences that both celestial bodies present in their composition.

3. Moon characteristics

The moon is a rocky celestial body. Its diameter is 3,474 kilometers (a quarter of the diameter of planet Earth) and it is characterized by having a surface with deep craters and high mountain systems. It is composed mostly of oxygen, silicon, calcium, magnesium and aluminum.

Its atmosphere (called “exosphere”) is weak and light, so it can not contain gases such as oxygen or maintain the temperature, which varies drastically between 110º and -170º Celsius.

The Moon does not shine with its own light, but reflects the light it receives from the Sun and therefore can be seen from Earth and can be seen in its different instances or “phases.”

These phases are produced by the variations of the position of the Moon with respect to the luminous star and the Earth, which generate more or less shadow on the satellite. The complete cycle that encompasses all phases of the Moon is 29 days, 12 hours and 44 minutes, also called “lunar month”.

4. Moon phases

The phases of the Moon are the changes of the illuminated part , which allow it to be fully or partially appreciated. The same face is always visible due to the synchronization that exists between what it takes to go around the Earth and turn on its own axis (both processes are carried out in 28 days).

The phases of the Moon are four and last about a week each:

• New Moon. It occurs when the Moon is closer to the Sun, its illuminated part is not visible from Earth and therefore it is almost imperceptible from the planet.
• Growing room It occurs when half of the Moon is illuminated: the right side is illuminated from the northern hemisphere and the left side is illuminated from the southern hemisphere. It occurs after the new moon and it is possible to observe it in the afternoon and in the first half of the night.
• Full moon. It is produced when the satellite is more distant from the Sun and one of its faces is fully illuminated, so the Moon is complete from Earth, throughout the night.
• Waning quarter. It occurs when half of the illuminated Moon is seen, but in a decreasing manner (unlike the crescent Moon) and, the visible half varies according to the Earth hemisphere from which it is observed. It is possible to see it at dawn and in the morning.

5. Moon Relief

The surface of the moon was studied through several expeditions (both manned and unmanned) made during the years 1969 and 1972.

From the samples obtained, it was found that it has a solid and rocky soil with a multitude of rubble, craters and basins . Among other reasons, the accidents of its relief are due to the fact that it does not have a consistent atmosphere that protects it from the impact of asteroids or other celestial bodies of smaller size.

It has mountains up to 9,140 meters high and some volcanoes that have been inactive for millions of years. It is estimated that, in addition to the mountain ranges, the plains or plateaus correspond to old seas, the largest detected is 1,120 kilometers in diameter.

There are also deep valleys called “lunar fissures” that reach 480 kilometers long and 3 kilometers wide. It is estimated that they were formed as a result of heat and expansion originated inside the satellite.

6. Moon movements

The moon performs two primary movements:

• The translation It is the movement of the satellite around the Earth, which takes 28 days, that is, approximately one month. In addition, it performs the movement of translation around the Sun.
• Rotation. It is the rotation of the satellite on its own axis and in an eastward direction that it also performs in 28 days.

The orbit of the Moon is inclined at a different angle from that of the Earth and the Sun, so that only two points of its path can produce eclipses of the Sun and Moon, respectively.

When the satellite is aligned exactly between the Sun and the Earth, a lunar eclipse occurs (occurs when the planet interposes between the luminous star and the Moon).

7. The tides

The gravitational force of the Moon influences the tides on Earth . When both stars are at a close distance, part of the mass of terrestrial water that faces the Moon is attracted to it and the flow of terrestrial water increases.

The Sun also exerts influence on the tides due to its gravitational force, but with less intensity due to its distance from the Earth.

The tides do not always vary at the same time, but depend on the phases of the moon and its alignment with the Sun. They can be:

• Spring tides. They are those high tides that are generated with the new Moon, in which the satellite and the Sun align, merging both gravitational forces.
• Dead tides They are those small tides that are generated during the phases of the crescent and waning Moon.