Moon Facts

The Moon is Earth’s own natural satellite and closest neighbor. It is the fifth-largest natural satellite in the solar system. The Moon is also the second densest natural satellite in the solar system. The Moon’s gravity affects Earth causing many natural phenomena such as tides.

Moon Profile

Interesting Moon Facts

  • The moon is the Earth’s only natural satellite.
  • It takes nearly 27 days for the moon to revolve around the earth once.
  • The moon is the fifth-largest natural satellite in the solar system.
  • Only one side of the moon is visible to us from the surface of the earth.
  • The radius of the moon is nearly 1400 km.
  • The moon is responsible for causing tides on the earth.
  • Gravity on the moon is nearly one-sixth of the gravity on Earth.
  • The moon is around 3,84,400 km away from the Earth.
  • Only 12 humans have visited the Moon as yet.
  • The moon is known to have several phases.
  • The moon is the brightest object in the night sky.
  • The moon is slowly moving away from the Earth.
  • The moon is the only celestial object other than the earth that has been physically visited by human beings.
  • The moon has not been named after any God. It was named as moon as at that scientists did not know that other planets also had moons.
  • The temperature on the moon can vary from -173 °C to 127 °C.
  • More than a hundred spacecrafts have visited the moon so far.
  • Once every year the moon appears to be nearly 14% larger than it does on a normal night. This moon is called a super moon.
  • Astronauts have brought more than 382 samples of rocks and other material from the Moon back to the earth. The samples are still being studied.

What is the Moon? 

The Moon is an astronomical object that revolves around the earth every 27 days. It is planet Earth’s only natural satellite. It is the fifth-largest natural satellite in the solar system. After Jupiter’s moon “Io” the moon is the densest natural satellite in the solar system.

The moon was formed 4.5 billion years ago, which is around 50 to 60 million years after the formation of the solar system. The rotation of the Moon with the earth is synchronous that is from the Earth we can only see one face of the Moon.

It is not clear how exactly the moon originated but it is believed that it was created as a result of the collision of a Mars-sized object with the earth. Some people also believe that the moon was initially created at another part of the solar system but it was gravitationally captured by the earth.

History

The moon has been known to mankind since the beginning of time because of obvious reasons. However, the Greeks were the first ones who tried to study and understand it. A Greek astronomer called Anaxagoras was the first one to discover that the moon did not have a light of its own.

Galileo Galilei
Galileo Galilei

Another Greek astronomer Aristarchus measured the distances between the earth and the sun, and earth and the moon. He also tried to measure the sizes of the moon relative to the earth. At around 150 BC it is discovered that the moon is responsible for causing tides on the earth.

Much information was discovered about the moon until the invention of the telescope. Galileo Galilei observed the moon through the telescope and discovered that it had a rough surface consisting of mountains and craters which was contradictory to the belief of ancient Greeks about the moon being smooth. Louis Daguerre took the first picture of the moon in 1839.  

Appearance

The moon is the brightest object in the night sky. It is the most obviously distinguishable celestial body from the surface of the earth. It has a silver-grey color with dark grey patches all over its surface.

Sometimes the moon is also visible during daytime or before sunset. The moon is non-luminous that is it doesn’t have a light of its own. It reflects back the light of the Sun. Actually, it only reflects back about 7% of the light that it receives. 

The moon does not appear to be the same every night. It changes its appearance. Sometimes it is seen in the form of a circle and other times in the form of a semicircle. On some nights it is not visible at all. The shapes of the Moon are governed by phenomena called the phases of the Moon. 

Size

The Moon has a mean radius of 1371 km. The moon is around 384,400 km away from the Earth.

Surface & Composition

The main components of the Moon are silica, aluminum, and lime. The moon has a crust, core, and mantle.

  • The crust of the moon is about 50 km thick. It is made up of elements like oxygen, magnesium, calcium, silicon etc.
  • The mantle of the moon is made up of magnesium, silicon, iron, oxygen etc.
  • The core of the moon is rich in iron content and has a radius of nearly 240 km. A partially molten layer exists around the core the radius of which extends to up to 500 km.

Magnetic field

Millions of years ago the Moon may have had a strong internal magnetic field. However, it is very weak today. The magnetic field on the moon is about a thousand times less than that on the earth.

Gravitational Forces

The moon is the second densest natural satellite in the solar system. Gravity on the moon is nearly one-sixth of that on the Earth.

Atmosphere

Due to a weak gravitational force, the moon has a very thin and weak atmosphere. It is called the Exosphere. Unlike the earth atmosphere the atmosphere on the moon does not provide any protection from the harmful radiations coming from the Sun. 

Orbit & Rotation

The approximate distance of the moon from the earth is about 3,84,000 km. It takes close to 27 days for the moon to revolve around the earth once. Interestingly, the time that the moon takes to rotate about its own axis is also close to 27 days. This is the reason why we always see the same side of the moon from the Earth.

Phases Of The Moon

The moon is known to have phases. The phases of the Moon are nothing but its appearance from the Earth at different times.

Phases Of The Moon

New Moon

The primary phase of the moon is called a New Moon. It happens when the sun and the moon are in alignment. In this phase, the Earth and the Sun are on the opposite sides of the Moon. This means that the moon lies between the sun and the earth.
In this phase, the moon cannot be seen directly from the surface of the earth as its dark side will be facing towards the earth.

Waxing Crescent Moon

In this a chain silver portion of the moon is visible to the naked eye.

First Quarter Moon

The next phase is the first quarter moon. It is the second primary phase of the Moon. It means that the moon has reached the first quarter of its orbit. It is also called half-moon. As the name suggests we can see half or 50% of the Moon from the surface of the earth.

Waxing Gibbous Moon

In this phase, the shape of the moon that can be seen is more than half but less than a full circle. It is an intermediate phase.

Full Moon

As the name suggests in the space the moon is entirely visible that is in the form of a perfect circle. In this phase, the Earth lies between the sun and the moon.

Waning Gibbous Moon

The next wave is called the waning gibbous moon. In this phase a little less than the full moon is visible. It is also an intermediate phase.

Half-Moon

The next primary phase is the half-moon in which the moon is visible in the form of a semicircle. The shape that is visible is opposite to the one visible in the first quarter.

Waning Crescent Moon

This is the last phase and mirror opposite of the Waxing Crescent Moon. In this phase the moon wanes until it becomes a New Moon.

This whole process lasts for about 27 and a half days.

Lunar Eclipse

A lunar eclipse is a phenomenon that occurs when the moon goes behind the Earth into its shadow. This means that the Sun, the Earth and the Moon are exactly all very closely aligned. The Earth lies exactly in between the Sun and the Moon. Hence in lunar eclipse the earth completely blocks the light of the Sun from reaching moon.

The light that the Moon reflects, that is the one which has been refracted by the Earth’s atmosphere. Due to scattering of light the moon appears to be reddish or orange in color. Hence a total lunar eclipse is also called a blood moon. This phenomenon lasts for a few hours.

A lunar eclipse can be seen from all parts of the earth at night and no protective glasses are required to see it. A lunar eclipse can only be seen on the night of a full moon. Another kind of lunar eclipse that is a partial lunar eclipse is a phenomenon in which small portion of the Moon passes through Earth’s shadow. This can also be easily seen by the naked eye. 

There can be about 0 to 3 total lunar eclipses in one year.

Exploration

For thousands of years, astronomers on the earth observed the moon with the naked eye. The invention of the telescope marked an important event in the history of astronomy making the telescope the most effective and reliable means of observing celestial bodies.

On 14th September 1959, Luna 2 space probe by the Soviet Union that is Russia made a landing on the surface of the Moon making it the first manmade object ever to land on the surface of the moon. It provided photos of the surface of the Moon and the first observations about the Dark Side of the Moon.

In 1962 NASA launched its first spacecraft to the moon. It was called Ranger 4. A decade after Luna 2, in 1969 NASA’s Apollo 11 Space Program became the first space mission to successfully land humans on the moon. Neil Armstrong and Edwin Aldrin created history by becoming the first human beings to ever set foot on the moon.

Many other spacecrafts were launched and sent to the moon after this. Today many countries like India, China, Japan, etc. have successfully sent spacecrafts to the moon. Many future missions to the Moon have also been planned and approved.

Potential for Life

No evidence of life has ever been found on the Moon. The conditions on the Moon are not fit to sustain life. The magnetosphere on the moon is very thin and water is scarce. Hence it is unlikely that the Moon could ever support life.

However, the Moon could be colonized by humans in the future. It is also the only celestial body other than the earth where human beings have set foot so far. It is also said that the moon could become a site for us to go to Mars. However, this is only a future possibility.

Moon in Pop Culture

As the Moon is the closest celestial body to the Earth it has been a huge part of pop culture here. It has caught the curiosity of many artists and it was found mentioned in their films and books.

One of the first search works of art is the 1865 novel called from Earth to the Moon by Jules Verne. In this novel Jules Verne has made extremely accurate predictions about how the first mission to the moon might be.

The first film to feature the moon was a French short film called Le Voyage Dans la Lune or a trip to the moon. Today the moon is one of the most popular celestial bodies when it comes to movies and TV shows. The moon is also mentioned in hundreds of songs in many languages. The moon is also considered a God and worshipped in many cultures.

Timeline

  • 1610: Galileo Galilei observes the Moon through a telescope for the first time
  • 1958: USAF makes first attempt to launch a spacecraft beyond the Earth’s orbit with Pioneer 0
  • 1959: Luna 2 of USSR makes an impact on the Moon surface
  • 1966: Luna 9 becomes the first spacecraft to successfully land on the Moon
  • 1969: Neil Armstrong and Buzz Aldrin become the first humans to land on the Moon with Apollo 11
  • Present: Several future missions to the moon have been proposed or are under development

References

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