Characteristics of the Moon

The Moon is one of the celestial bodies in the solar system. It is the fifth largest natural satellite and the only one on Earth. Its equatorial diameter is 3,474 km and it is essentially made up of rocks.

Although there is still no concrete theory about its origin, one of the most accepted explanations holds that the Moon is the result of the collision of a celestial body with the Earth.

This impact occurred about 4.5 billion years ago and, as the magma of that new satellite cooled, about 100 million years ago, what we know today as the lunar crust was formed.

The word moon has its origin in Latin and means “luminous” or “the one that illuminates”. In Greek mythology, Selene is the lunar goddess, hence, in the scientific or academic field, terms derived from this name are used to designate concepts associated with the satellite, such as selenography, which is the part of astronomy that is responsible for studying Moon.

Although other planets also have their moons and they have their own names, the reason why the terrestrial satellite is only called “moon” has to do with the fact that it was not known about the existence of other celestial bodies orbiting around other planets. .

For this reason, it was named Luna, under the assumption that it was a one-of-a-kind body. Until in 1610, Galileo Galilei was able to observe for the first time 4 moons orbiting Jupiter, which were called Io, Europa, Ganymede and Callisto. Today, this planet is known to have more than 60 natural satellites.

Characteristics of the Moon

Current technology allows lunar craters to be seen more clearly from Earth.

The lunar surface is full of rocks, basins and craters, the latter are the result of multiple collisions of celestial objects that have passed through its exosphere, a very weak atmosphere that does not provide any protection.

In addition to this, the Moon has volcanoes, but they are inactive. The event that does occur frequently is dust storms caused by lunar winds, which kick up regolith (fine coal dust) and rock debris.

These are other salient features of the moon:

  • It is 400 times smaller than the Sun, but being closer to Earth, they are perceived almost the same size.
  • The temperature ranges between -248ºC and 143ºC.
  • Its approximate distance from Earth is about 384,400 km.
  • Gravity on the moon is 0.166 that of Earth. That means that a person weighing 60 kilos on the Moon would only weigh 9.96 kg.
  • Its surface area measures 38 million km.
  • Its mass is 7.349 x 10²² kg.
  • The density of the moon is 3.34 g / cm³
  • Its volume is 2.1958 × 10¹⁰

Rotational and translational movements of the Moon

The moon rotates on its own axis (rotational movement) in 28 days. While the time it takes to rotate around the Earth (translational movement) is about 29 days, approximately. The fact that the two movements occur almost simultaneously is what makes us always see the same face of the Moon.

The Moon also makes a translational movement around the Sun, since being the Earth’s natural satellite, the planet “drags” it with it when making its translation. In this case, the movement lasts for 365 days.

Lunar libration

Although only one side of the Moon is visible, what we see from Earth is not exactly 50% of its surface, but 59%. This is due to an effect called libration.

The orbital speed of the moon is not constant, and this allows parts of its eastern and western edges to be more visible during its translational motion. This is known as libration in length.

While the 5 degrees of lunar inclination with respect to the plane of its orbit allows it to be seen about 6º 30 ‘more than its south pole, which is known as a libration in latitude.

Moon phases

As the moon makes its translational movement around the Earth, the Sun illuminates different parts of the satellite, which gives rise to the lunar phases.

New Moon: in this phase, the Moon is between the Earth and the Sun, which hides the lunar fraction closest to our planet.

Full Moon: the Earth is between the Moon and the Sun and this illuminates the half of the satellite that is closest to the planet.

Fourth lunar: in this case, the Moon is in intermediate positions, so the portion closest to the Earth is only half illuminated, that is, a quarter of its surface. It will be a crescent moon if the illumination of that room tends to increase, and a waning moon if the illumination of that portion tends to decrease.

Influence of the Moon on the tides

The translational motion of the Moon is not exactly around the Earth’s orbit. More precisely, both bodies revolve around the center of each other’s masses.

When the moon is located at a point on the planet, the action of these gravitational forces generates an elevation of the waters above sea level (high tide). While at the opposite end of the planet, the waters descend (low tide).

This happens twice a day, so that the same place will have a high tide and a low tide daily.

Space missions to the Moon

Buzz Aldrin, second man to reach the Moon. Apollo 11 Mission , 1969.

Attempts to explore the lunar surface began in the former Soviet Union with the Luna program, which began in 1959 and which made it possible to photograph the far side of the satellite, land on its surface and orbit it, in different missions.

For its part, the Ranger program, of American origin, began in 1961 sending photographic reconnaissance ships and unmanned spacecraft until, finally, the Apollo 11 space mission, belonging to the Apollo program, achieved the feat of bringing humans to the lunar surface. in 1969. Astronauts Neil Armstrong and Buzz Aldrin were the first and second man to set foot on the Moon, respectively.

From there, missions from various countries have been sent to the moon or its orbit for scientific purposes. In 2019, NASA announced the construction of a lunar base that will run on solar energy. The goal is to make human presence possible for extended periods starting in 2024 and serve as a starting point for future missions to Mars.


by Abdullah Sam
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