# Wikijunior:Solar System/Mars

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!♂.svg "♂"){width="80"} **Mars Facts**:

-   Mars is red because of rust in the surface rocks
-   A volcano on Mars called *Olympus Mons* is the highest mountain in
    our Solar System.
-   Mars has polar ice caps that look like the ones on
    ../Earth/.
-   Mars has ancient river beds where scientists think liquid water
    flowed millions or billions of years ago.
-   The *Tooting* crater on Mars was named after a suburb in London
    because the discoverer \"thought \[his\] mum and brother would get a
    kick out of having their home town paired with a land form on
    Mars\".

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Mars is the fourth planet from the Sun. It is called a *terrestrial*
planet because its outer layers are made of rocky material like the
Earth.

## How big is the planet?

!Comparison of the size of Mars and the
Earth
Mars is the second smallest of the eight major planets in the Solar
System. Only Mercury is smaller. It is nearly 7,000 kilometres (km)
wide; just over half the width of the Earth. Its volume is about 15% of
the Earth. Since a lot of the Earth is covered by water, the total
surface area of the Mars is nearly as large as all of the land on the
Earth. It is possible that its size may eventually permit human
colonies. 

## What is its surface like?

center\|thumb\|upright=3\|A panorama view from the Mars rover
*Spirit*.

The surface of Mars is a lot like a desert on Earth; it is very dry and
dusty, but it is also very cold. There are a lot of loose rocks and
dunes of fine sand. Crater impacts mark the surface, but these are not
as common as on the Moon. One of the craters is the huge *Hellas
Planitia*. It is about half the size of the continental United States.
The southern half of the planet has more craters than in the north. The
south is also higher in elevation.

!An overhead view of *Olympus Mons*, the highest mountain in the Solar
System.
There is an area on Mars called the *Tharsis Bulge*, which has four huge
volcanoes. These volcanoes have not erupted for millions of years. The
largest volcano is called Olympus Mons. It is 27 km tall, making it the
highest mountain in the Solar System; *more than three times* higher
than Mount Everest on Earth. It is 625 km across and takes up an area as
big as the US state of Arizona. Mars also has a huge canyon called the
*Valles Marineris*. It is much bigger than the Grand Canyon on Earth. It
is 4000 km long, up to 7 km deep and up to 200 km wide. Scientists think
that when the *Tharsis Bulge* was created, the surface of Mars cracked
to form the *Valles Marineris*.

Like the Earth, Mars has ice caps at its poles. However, they are made
from frozen carbon dioxide as well as ice. During the Martian winter at
each pole, the cap grows as carbon dioxide from the atmosphere freezes.
The cap shrinks again during the Martian summer. As on Earth, when it is
winter at one pole it is summer at the other.

In some places, there are dry *channels* that look like they were made
by running water. So, a long time ago Mars may have had lakes and
streams made of water. Now all of the water is frozen into ice under the
surface.

There is an atmosphere on Mars, but it is very thin. There is also much
more carbon dioxide in it than oxygen. (Oxygen is the gas we need when
we breathe in; carbon dioxide the gas we get rid of when we breathe
out.) So, we would need spacesuits to visit Mars. The atmosphere helps
protect the surface from smaller meteorites.

When Mars comes closest to the Sun, the atmosphere can stir up storms of
dust. Some of these storms are gigantic; they can cover the entire
planet in clouds of dust. Dust storms on Mars can last for hundreds of
days, with wind speeds of up to 200 kilometres per hour. Huge storms
like these have been seen from the Earth through telescopes.

{{  }}
{{/Mars}}

## How long is a day and year on this planet?

One day on Mars is only 39 minutes and 35 seconds longer than a day on
Earth (1.026 Earth days). A year on Mars is almost two Earth years long
(687 Earth days).

Much like the Earth, the axis of rotation of Mars is tilted at an angle.
This tilt causes seasons on Mars as it travels around the Sun. Summer
occurs on the half of the planet that is tilted toward the Sun, and
winter on the other half. After half a Martian year has passed, the
seasons are reversed. But these seasons are about twice as long as on
Earth.

## What is it made of?

!visualization of the Martian
interior.

The outer, rocky surface of Mars is called the crust. Most of the crust
is made from basalt, a type of rock made when lava grows cold.

Like the Earth, Mars has a thick layer of rock below the crust called
the mantle. The mantle is much hotter than the crust, and the mantle
rock is partly molten. But the crust on Mars has grown thick, so the
lava from the mantle no longer reaches the surface. There are volcanoes
on Mars, but they are no longer active.

At the center of Mars is a core made of the metals iron and nickel. If
Mars were the same size as the Earth, the core of Mars would be smaller
than the Earth\'s core. So a larger amount of Mars is made out of rock.
Because rock is lighter than the metals in the core, Mars has a lower
density than the Earth. 

## How heavy would I be on Mars?

!Detailed picture of Mars

If you were on Mars, you would be lighter, as Mars\' gravity only has a
force about two fifths as strong as the that of Earth\'s. You could lift
objects that weigh almost three times as much compared to similar
objects here on the Earth. You could jump up almost three times higher,
and it would take much longer to fall to the ground from the same
height.

Even though it looks as though you would be like a comic-book hero on
Mars, there are some things you couldn\'t do. Although a big rock would
*weigh* less and you could pick it up, it would still have the same
*mass*. If you tried to catch it, it would knock you over, and if it
landed on you it would crush you. A car on the surface of Mars would
need the same amount of power to speed up, although going uphill would
be less of a problem. It may, however, need more room to stop. Because
of the reduced gravity a vehicle would not \"grip\" the ground on Mars
as strongly, but the constant mass would keep the vehicle moving just as
strongly, making it easy to go into a skid.

## Who was it named after?

In Roman mythology, Mars was the god of war and agriculture. The planet
Mars was named this because the planet looks red like blood, from rust
in its surface rocks.

## Who discovered Mars?

Nobody knows, but the earliest records we know of were by Ancient
Egyptians, more than 4000 years ago, noting Mars\' movement. On one
pharaoh\'s tomb, named *Seti I*, Mars is drawn on the ceiling. The
Babylonians (in the Middle East), Chinese, and Greeks also studied Mars
more than 3000 years ago. The Greeks learned about Mars from the
Babylonians, and since the Babylonians called it their god of war, named
*Nergal*, the Greeks called it their own god of war, *Ares*. Exploration
of Mars was first attempted in 1960, with Mars 1. It failed, along with
several other missions by the Soviet Union in the 1960s. The first
successful mission to Mars was in 1964, by Mariner 4, by the U.S. Most
of the other Mariner missions to Mars were successful. The last Mariner
mission to Mars, Mariner 9, got there in the midst of a dust storm, and
orbited the planet for several months before it could get a good look at
the surface. So far, all these missions were flybys or orbiters. The
first spacecraft to land on Mars was Viking 1 in 1976. Viking 2 landed
19 days later. Together, they took many good pictures of Mars\' surface.

<table>
<tbody>
<tr class="odd">
<td><p><code>{{multiple image</code></p></td>
<td><p>align = left</p></td>
<td><p>width1 = 100</p></td>
<td><p>width2 = 110</p></td>
<td><p>width3 = 122</p></td>
<td><p>width4 = 123</p></td>
<td><p>width5 = 100</p></td>
<td><p>width6 = 196</p></td>
<td><p>image1 = Mars Viking 11h016.png</p></td>
<td><p>caption1 = Viking 1 lander site (February 11, 1978).</p></td>
<td><p>image2 = PIA00563-Viking1-FirstColorImage-19760721.jpg</p></td>
<td><p>caption2 = Viking 1 lander site (1st color, July 21,
1976).</p></td>
<td><p>image3 = First Color Image of the Viking Lander 2
Site.jpg</p></td>
<td><p>caption3 = Viking 2 lander site (1st color, September 5,
1976).</p></td>
<td><p>image4 = Vl2 22g144-MarsViking2-19770925.gif</p></td>
<td><p>caption4 = Viking 2 lander site (September 25, 1977).</p></td>
<td><p>image5 = Mars Viking 21i093.png</p></td>
<td><p>caption5 = Frost at Viking 2 site (May 18, 1979).</p></td>
<td><p>image6 = Mars Viking 12a240.png</p></td>
<td><p>caption6 = Martian sunset over Chryse Planitia at Viking 1 site
(August 20, 1976).</p>
<p><code>}}</code></p></td>
</tr>
</tbody>
</table>

Next Topic: Asteroid belt

## References

-   Steven W. Squyres, *Mars*, World Book Online Reference Center, World
    Book, Inc., 2004.
    1
    2
-   \"a *terrestrial* planet\"
    3
-   \"How big is the planet?\"
    4
    5
-   \"How long is a day on this planet?\"
    6
    7
-   \"What is it made of?\" Steven W. Squyres, *ibid.*

ar:ويكي الأطفال:نظام
شمسي/المريخ bs:Wiki
junior Sunčev sistem/Mars
de:Wikijunior Sonnensystem/
Mars
es:Wikichicos/Sistema_Solar/Marte
nl:Wikijunior:Zonnestelsel/Mars
pl:Wikijunior:Układ_Słoneczny/Mars
fi:Wikijunior_Aurinkokunta/Mars
zh:Wikijunior:太阳系/火星
