# Wikijunior:Solar System/Moon

{{/Coolfacts\|=
1\|!☽︎.svg "☽︎"){width="80"}\|=
2\|Moon Facts\|= 3\|

-   When we look at the Moon from Earth, we always see roughly the same
    side. Until Luna 3 sent back photos in 1959,
    no-one knew what the other side looked like.
-   The Moon is nearly twice as big as
    ../Pluto/.
-   The \"Man in the Moon\" isn\'t always seen as a man. People from
    India see an old woman with a spinning wheel. People from Mexico see
    a rabbit!
-   The Moon isn\'t that small compared to the Earth - it\'s actually
    the largest moon in the solar system, relative to the size of its
    planet. Sometimes the Earth and Moon together are called a *binary*
    or *double planet system*.
-   The Moon is the fifth largest moon in the solar system.
-   In 2002, another object appearing to be an asteroid was observed
    orbiting around the Earth. Later it was found to be a rocket
    booster.

}} ! The Moon is our nearest neighbour in
space.

## How big is the moon?

!Comparison of the size of the Moon and the
Earth
Most of the planets in the Solar System are much bigger than their
moons, but the Earth and the Moon are much closer in size. The Moon is
just under 3,500 kilometers (km) wide. That\'s over a quarter of the
size of the Earth (about 12,600 km wide) as you can see in the picture
below. Because of this, the Earth and Moon together are sometimes called
a *binary* or *double planet system*.  {{
 }}

## What is the moon\'s surface like?

!Astronaut Harrison Schmitt collecting rocks from the Moon during the
Apollo XVII
mission.
!A map of the
moon. The Moon has
no atmosphere. It also has no liquid water on its surface. During the
day it becomes very hot, but at night it is icy cold. A person visiting
the Moon needs an air supply and a special suit.

The Moon has many *craters* on its surface. The largest one is called
the *South Pole-Aitken Basin* and is roughly 2500 km across.

We think nearly all the craters on moons or planets were made by huge
rocks hitting them a long time ago. These collisions are called
*impacts.*

Some of the craters on the Moon look as if they have rays coming out of
them. These rays are rocks thrown across the Moon by the impacts that
made the craters. Some of the craters around the poles of the Moon may
have ice in them.

There are also darker areas called *maria* (said \"MARR-ee-ah\"). These
are large pools of lava that cooled a long time ago. Most maria are on
the side of the Moon we see from Earth. The lighter areas on the Moon
are highlands.

## How long is the Moon\'s revolution?

The Moon takes just over 27 Earth days to *rotate* (rotate means spin
around) once.

## How long is a year on the moon?

The Moon also takes just over 27 days to *orbit* (move around) the
Earth. This is why we always see the same side of the Moon when we look
from the Earth. We call this side the *near* side. The other side we
call the *far* side. In 1959, a probe called *Luna 3* sent back pictures
of the far side. That was the first time anyone saw what it looked like.

## What is the Moon made of?

The surface of the Moon is made of rocks and dust. The outer layer of
the Moon is called the *crust*. The crust is about 70 km thick on the
near side and 100 km thick on the far side. It is thinner under the
maria and thicker under the highlands. There may be more maria on the
near side because the crust is thinner. It was easier for lava to rise
up to the surface.

We think the Moon has a small *core* (center) about 300 km across. The
core is composed of solid iron. Because the core is solid, the Moon does
not have its own magnetic field.

## How much would the Moon\'s gravity pull on me?

If you were on the Moon, it would pull you down about a sixth as much as
the Earth does, so you\'d weigh a sixth as much. So would anything else.
That\'s why it was much easier for the astronauts visiting the Moon to
pick up rocks there.

## Who is the moon named after?

!The goddess Diane, the goddess of the Moon in Roman
mythology
The names *Moon* and *month* both come from the ancient Greek name for
the Moon, *Mene*. There have been other names for the Moon, like
*Selene* and *Luna*. Selene was the Greek goddess of the Moon. Luna was
the Roman goddess of the Moon. The Roman people also associated their
goddess Diana with the Moon.

## Who discovered the Moon?

Ancient Greece and Ancient China noted over 2000 years ago that the
light from the Moon is reflected from the Sun. Also, Ancient Greece
noted that the Moon causes tides on Earth. More recently, Luna 1 was the
first spacecraft to perform a flyby of the moon. Luna 2 was the first
spacecraft to land on the moon, and Luna 3 was the first to photograph
the far side of the Moon which you can not see from Earth. Luna 1
through 3 all were launched in 1959. Surveyor 3, in 1967, was the first
to examine the soil of the Moon. It dug to 17.5 cm. In 1969, Apollo 11
was the very first spacecraft to land people on the moon.

Next Topic: Mars

## References

\"The Moon is just under\...\" 1
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\"So the Earth and the Moon together\...\"
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\"The Moon does not have any atmosphere.\"
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\"During the day it becomes\...\"
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\"The largest one is called\...\"
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\"These rays are rocks\...\"
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\"Some of the craters around the bottom\...\"
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\"There are also darker areas\...\"
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\"The lighter areas\...\"
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\"The Moon takes just over 27\...\"
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\"We call this side\...\"
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\"The other side we call\...\"
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\"The surface of the Moon\...\"
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\"\...it would pull you down\...\"
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\"The names \"Moon\" and\...\"
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ar:ويكي الأطفال:نظام
شمسي/القمر bs:Wiki junior
Sunčev sistem/Mjesec
de:Wikijunior Sonnensystem/
Mond
zh:Wikijunior:太阳系/月球
