Moon - Formation, structure and facts - Information For kids

Near side of the moon
Near side of the moon | Source

This hub gives detailed information on the formation of the moon, the different theories involved in the formation of the moon, the structure of the moon and some interesting facts about the moon.

We all live on a planet called Earth. Did you know that the Earth had a satellite called the Moon? Yes, it is the Earth’s natural satellite and is the fifth largest satellite in the solar system and the biggest satellite to a planet in the Solar system. It orbits around the earth once every 27.3 days and it has its same side facing the earth at all times. The average distance between the moon and the earth is 384,400kms. In this hub we will look at how the moon was formed, the structure of the moon and other characteristics of the moon.

The far side of the moon
The far side of the moon | Source

The Moon is a satellite that resembles a planet also called "The light that rules the night". It is almost one quarter of earth’s diameter and its gravity is just one sixth of the earth’s gravity because of its relatively small size as compared to Earth. The density of the moon is relatively low compared to the earth because of its small iron core. There is very less volatile substances in moon, which confirm the high baking surface of the moon. The identical oxygen isotopes suggest that the earth and the moon formed at relatively similar distances from the sun. The moon is believed to have formed 4.5 billion years ago, and there are a few theories behind as to how the moon was formed.

Fission theory
Fission theory | Source

The fission hypothesis or theory, as the name explains, where the moon was formed as a result of simply breaking off from earth and it is believed that a basin in the Pacific Ocean is a proof for that, although it is very much younger compared to the age of the moon.

Capture theory
Capture theory | Source

Lunar capture or the capture theory, again as the name explains, says that the moon which was somewhere far away from the earth was captured as a result of earth’s gravitational field.

Co-accretion theory
Co-accretion theory | Source

Co-accretion theory or co-creation theory, that states that the earth and the moon were formed of similar building blocks in the same part of the solar system, but does not account for the fact that moon has very less iron content compared to earth.

Birth of the Moon

The Giant impact theory
The Giant impact theory | Source

The giant impact or the ejected ring theory is the theory that is believed to be true at the moment. According to this theory, the earth which was still young around 4.5 billion years ago, was collided by a planetary object, roughly the size of Mars and this Giant collision released large amount of debris from the mantle of the earth into the earth’s orbit, which was enough for the moon to form, and hence the reason why moon has far lower percentage of iron.


Cross-section structure of the moon
Cross-section structure of the moon

The Structure of the moon:

Very similar to the structure of the earth, the moon has the crust, the mantle and the core, which are believed to have formed as a result of the fractional crystallization of magma after its formation around 4.5 billion years before. The moon’s diameter is roughly 3474kms

The crust:

The moon’s crust is anorthositic in nature. According to a science dictionary, Anorthosite means an igneous rock consisting almost entirely of plagioclase feldspar, especially the labradorite variety, and these have been identified among the rock samples collected from the moon. The crust contains minerals like, oxygen, silicon, magnesium, iron, calcium and aluminium. Also traces of titanium, uranium, thorium, potassium and hydrogen are present. The thickness of the crust is between 50 km and 65 km.

The Mantle:

The mantle is divided into upper mantle, middle mantle and lower mantle. It has larger iron content than earth’s mantle. Moon-quakes are believed to occur in the moon’s lower mantle periodically due to tidal effects between the earth and the moon. The mantle is between 800 – 1000kms thick. The lower mantle is partially fluid and contributes to the moon-quakes which can erupt on the lunar surface.

The core:

The core is just 20% of the size of the moon, which leads to its lower density and gravitational field. It is believed that the lunar core is metallic iron in its alloyed state with traces of sulphur and nickel. The core has two layers, the solid inner core which is about 160kms in radius and the fluid outer core which is about 350kms in radius. The complete core works out to be around 500kms in radius.

Lunar Landscape
Lunar Landscape | Source

Lunar landscape:

The moon has basically 2 different types of terrains, the Maria and the highlands. Besides these there are other features like the rilles, domes, wrinkle ridges, grabens, impact craters, regolith, lava tubes etc.

Maria-dark regions we see on the moon
Maria-dark regions we see on the moon | Source

The Maria:

The Maria is the dark-coloured regions we see on the moon. These are lowland basins and they cover 15% of the moon’s surface, which is almost a third of the side facing the moon. These are mostly found on the side of the moon facing the earth which is also called the near-side of the moon. These are less cratered and are believed to be filled in by flows of lava as they have patterns similar to lava flow. There are also dark mantle deposits, which form part of the Maria region. These are pretty younger regions when compared to the highlands, and are mostly composed of basalt.

The lunar highlands
The lunar highlands | Source

The highlands:

The highlands cover almost 85% of the lunar surface and are heavily cratered. They are very ancient regions when compared to the Maria. These are anorthositic in nature. The far-side or the side of the moon away from the earth is very similar to these highlands area, and are heavily cratered.

The Moon for Kids

Phases of the moon
Phases of the moon

The phases of the moon:

When you watch the moon over a month’s time, you can see that it has different phases. The moon does not have any light of its own, and it reflects the light from the sun falling on it. Since the moon rotates or orbits around the earth, it reflects different amounts of light, depending on its position relative to the sun. These are called the phases of the moon.

On occasions, the moon passes between the earth and the sun, thereby causing a solar eclipse, and also when the moon passes directly behind the earth away from the sun, it causes a lunar eclipse. During a Lunar eclipse, the moon is reddish orange in colour and this is due to the limited rays from the sun and rays diffracted around the edge of the earth that fall on the moon.

Lunar Eclipse
Lunar Eclipse
Solar eclipse
Solar eclipse

The volcanic activities due to moon quakes on the moon are responsible for the Maria, which are low lying regions where the lava flows into. There has been no evidence of tectonic movements on the lunar landscape as compared to the ones on earth.

There are roughly 300,000 big craters wider than 1 km found on the near side surface of the moon and these are believed to have formed due to the impact of comets and asteroids on the surface of the moon. Due to extreme temperatures on the surface of the moon, water will quickly decompose off due to solar radiation. However on the side of the moon which is permanently dark, and where there are no solar radiation for example the poles, there can be water ice, which would have been deposited by comets or produced by the reaction of lunar rocks which are rich in oxygen, and hydrogen from the solar wind.

Tidal bulge
Tidal bulge
Moon earth comparison
Moon earth comparison

Some interesting facts about the moon:

  • The moon has a very small magnetic field compared to that of earth’s. Its gravity is too low as compared to the earth, as due to the reasons discussed earlier.
  • The mass of the moon is 7.35 x 1022 kg, which is roughly 0.0123 times the mass of the earth.
  • The density of the moon is 3.34 gm/cm3 which is roughly 0.6 times the density of earth.
  • The surface temperature of the moon can vary between 204o C during the day to -205o C during the nights.
  • The moon has no atmosphere, which means no sound can be heard and the sky is dark all the time due to no scattering or dispersion of light.
  • The rise and fall of ocean tides on earth is due to the gravitational pull of the moon on the earth.
  • The moon’s orbit around the earth is an ellipse
  • For the moon to complete its phases once, takes 29.5 days and that is called one Lunar month.
  • The moon orbits around the earth at a speed of 3683 kms/hour
  • The moon has no wind or weather, because it has no atmosphere and hence the footprints left by astronauts will stay there for millions of years.
  • The full moon has different names as to which month it occurs.
  • The moon is the only extra-terrestrial body that has ever been visited by humans.

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Comments 16 comments

livingsta profile image

livingsta 8 months ago from United Kingdom Author

Hello Lee Cloak, thank you for passing by. I am pleased that this hub was educative for you. Thank you so much for your votes.


Lee Cloak 17 months ago

A really great hub, i look up at the moon most nihjts yet i knew next to nothing about, very interesting, voted up, thanks , Lee


livingsta profile image

livingsta 3 years ago from United Kingdom Author

Hi kidscrafts, thank you for reading. Yes, learning becomes more interesting with pictures, demonstrations and animations. It also helps them and everyone understand things better. Thank you so much for the votes and appreciation. Have a great week ahead.


kidscrafts profile image

kidscrafts 3 years ago from Ottawa, Canada

Excellent information for kids to learn! I like the fact that you also used a lot of pictures! I find that visual is so important for kids to learn better!

Voted up, useful and interesting!


livingsta profile image

livingsta 3 years ago from United Kingdom Author

Thank you Kashmir56, I am glad you found it useful for kids. Thank you for the appreciation. Have a great week ahead!


kashmir56 profile image

kashmir56 3 years ago from Massachusetts

Great hub and lot of interesting and useful information to keep kids fascinated and interested in learning more about the moon. Well done !


livingsta profile image

livingsta 3 years ago from United Kingdom Author

Thank you so much Toknowinfo. I am glad it was useful and thank you for the votes!


toknowinfo profile image

toknowinfo 3 years ago

Great hub! I really learned a lot. Thanks for putting all this useful info together. All the best to you. Rated up, useful and interesting.


livingsta profile image

livingsta 3 years ago from United Kingdom Author

Thank you Thumbi7 :)


thumbi7 profile image

thumbi7 3 years ago from India

Very useful information!

Thanks for sharing


livingsta profile image

livingsta 3 years ago from United Kingdom Author

Thank you unknown spy! :)


unknown spy profile image

unknown spy 4 years ago from Neverland - where children never grow up.

great and well written hub!


livingsta profile image

livingsta 4 years ago from United Kingdom Author

Thank you Chiradeep!


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chiradeep 4 years ago from India

Wow! Beautifully presented and very good information for kids as well as adults.


livingsta profile image

livingsta 4 years ago from United Kingdom Author

Thank you so much Nell. I do understand what you mean. There is so much that we learn each day!

Thank you for the vote and share too!


Nell Rose profile image

Nell Rose 4 years ago from England

Fantastic information about the moon! this is so useful for kids and adults alike, we all think we know about the moon, but even I sat here reading saying to myself, really? never knew that! lol! wonderful! voted up and shared, nell

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