Our Companion- The Moon

Our Major Partner - Moon

Introduction- Our moon is the brightest object in the night sky. It is a natural satellite of earth revolving around it since the time it was formed. It has a very big contribution to make life possible and comfortable on earth. It is a dependent body on which earth depends but it is not a part of star constellations.

Formation

Many theories are stating how the moon became the natural satellite of the earth. We will discuss them one by one.

1. Capture Theory- This theory states that the Moon was a celestial body which by chance entered the solar system from outside. While crossing the Earth's orbit the gravity of earth influenced the moon and got tidally locked with the moon. But the fact which goes against this theory was that Moon was not so small than the Earth and thus the earth couldn't capture the moon as its gravity is n't strong enough to capture the moon. As a result, this theory was rejected.

2. Fission Theory - This theory was proposed by George Darwin in which he stated that the earth in its ancient times spins rapidly due to which its some part expelled in the space and got combined after some time and formed our moon. But its drawback was that if this theory is true then the soil composition and type in both the bodies should be the same. But there is a large difference in the soil type of earth and moon. Due to this the fission theory was rejected.

3. Condensation Theory - This theory supports the idea that both the earth and moon were formed in that in the same nebula which created the solar system and the moon was formed in the orbit of the earth but if the moon was formed in the vicinity of the Earth then the composition of the earth and the moon should be nearly same. Also, this hypothesis does not have a natural explanation for the extra heat that the lunar material had received.

4. Giant Impact Theory - Giant Impact Theory is the most widely accepted Theory in Astronomy.

This proposes the idea that when the earth was newly formed in the solar system at that time it shares its orbit with mars sized planet named Theia but as time passed Theia got unstable and slowly it moved towards Earth resulting in a big collision with the earth which generated a large amount of heat. After this collision both the planets lost a large amount of debris. This lost debris got heated up due to the friction generated by the collision and began to revolve around the earth. After some time, this debris accumulated together and formed our Moon.

Structure

Like our Earth, The Moon is also composed of a core, mantle, and crust. At the center, there is a solid inner metallic core mainly composed of iron and a small amount of Nickel. Covering the inner core there is a molten outer core which increases the length of the core to 330 km.

Above the core are the mantle and crust. Differences in compositions between these layers tell a story of the Moon being largely, or even completely, composed of a great ocean of magma in its very early history.

 As the magma ocean began to cool, crystals began to form within the magma. Crystals of denser mantle minerals, such as olivine and pyroxene sank down to the bottom of the ocean. 

Lighter minerals, notably anorthositic plagioclase feldspar, crystalized and floated to the surface to form the Moon’s crust.

The crust has a thickness of about 43 miles (70 kilometers) on the Moon’s near-side hemisphere and 93 miles (150 kilometers) on the far-side. It is made of oxygen, silicon, magnesium, iron, calcium and aluminum, with small amounts of titanium, uranium, thorium, potassium and hydrogen.

Long ago the Moon had active volcanoes, but today they are all dormant and have not erupted for millions of years.

Surface

With a very thin atmosphere and a weak magnetic field, a steady rain of asteroids, meteoroids and comets strikes the surface of the Moon, leaving numerous craters behind. Tycho Crater is more than 52 miles (85 kilometers) wide.

Over billions of years, these impacts have ground up the surface of the Moon into fragments ranging from huge boulders to powder. Nearly the entire Moon is covered by a rubble pile of charcoal-gray, powdery dust and rocky debris called the lunar regolith. Beneath is a region of fractured bedrock referred to as the megaregolith.

The temperature reaches about 260 degrees Fahrenheit (127 degrees Celsius) when in full sun, but in darkness, the temperature falls down to about -280 degrees Fahrenheit (-173 degrees Celsius).

Water on the Moon

During the initial exploration of the moon, and the analysis of all the returned samples from the Apollo and the Luna missions, we thought that the surface of the moon was dry.

The first definitive discovery of water was made in 2008 by the Indian mission Chandrayaan-1, which detected hydroxyl molecules spread across the lunar surface and concentrated at the poles. Missions such as Lunar Prospector, LCROSS, and Lunar Reconnaissance Orbiter, have not only shown that the surface of the Moon has global hydration, but there are actually high concentrations of ice water in the permanently shadowed areas of the lunar surface.

Atmosphere and Magnetic Field 

The Moon has a very thin and weak atmosphere, called an exosphere. It does not provide any protection from the sun's radiation or impacts from meteoroids.

The early Moon may have developed an internal dynamo, the mechanism for generating global magnetic fields for terrestrial planets, but today, the Moon has a very weak magnetic field. The magnetic field here on Earth is many thousands of times stronger than the Moon's magnetic field.

Potential for Life

    The many missions that have explored the Moon have found no evidence to suggest it has its own living things. However, the Moon could be the site of future colonization by humans. The discovery of the Moon harbors water ice, and that the highest concentrations occur within darkened craters at the poles, makes the Moon a little more hospitable for future human colonists.

  In the coming years, Nasa is looking forward to send its astronauts back to the surface of the moon by 2024. The advantage that we will get after making a human base on the moon is that we will require less fuel to pursue our missions to other planets like Mars and moons like Titan. And also it will be a big achievement for mankind towards space development.

Importance Of Moon 

Our natural satellite moon which is one-fourth of the size of the earth but has a major contribution in making life possible on earth.

In its early stages, the earth rotates very fast and at that time, one day was only of 8 hours but after the formation of the moon, the earth experiences a gravitational force by the moon due to which its rotational speed has slowed down, increasing the length of the day to 24 Hours.

Another importance of Moon is that it makes the earth to be tilted at 22 and a half degrees which cause seasons on the Earth.

It also causes tides, creating a rhythm that has guided humans for thousands of years.

Thanks for giving your time to this post. Have a nice day.