[[File:Planets2008.jpg|400px|thumb|right|The [[Sun]], [[planet]]s and [[dwarf planet]]s of the Solar System. Compared with each other, the sizes are correct but the distances are not.]]
The '''Solar System''' is the [[Sun]] and all of the objects in [[space]] which [[orbit]] (go around) it. The Sun is orbited by [[planet]]s, [[Satellite (natural)|moons]], [[asteroid]]s, [[comet]]s and other things. The Sun is a [[star]]. It contains nearly all of the Solar System's [[mass]]. This means that it has strong [[gravity]]. The other objects are pulled into orbit around the Sun. The Solar System is in one of the arms of the [[Milky Way]] [[galaxy]].
There are eight [[planet]]s in the Solar System. In order of increasing distance from the Sun, they are: [[Mercury (planet)|Mercury]], [[Venus]], [[Earth]], [[Mars]], [[Jupiter]], [[Saturn (planet)|Saturn]], [[Uranus]] and [[Neptune]]. The first four planets are called [[terrestrial planet]]s. They are mostly made of [[rock]] and [[metal]], and they are mostly [[solid]]. The last four planets are called [[gas giant]]s. This is because they are large planets which are mostly made of [[gas]]. They also have much more mass than the terrestrial planets. [[Satellite (natural)|Moons]] orbit six of the planets. [[Planetary rings]] and [[cosmic dust]] orbit the [[outer planet]]s.
The Solar System also contains other things. There is the [[asteroid belt]] between Mars and Jupiter. Further out than Neptune, there is the [[Kuiper belt]] and [[scattered disc]]. Inside the Kuiper belt, there are [[trans-Neptunian object]]s which are mostly made up of [[ice]]s, [[water]], [[ammonia]] and [[methane]]. Four [[dwarf planet]]s are in the Kuiper belt. These are small planets which are just large enough to be [[sphere]]-shaped. There are five dwarf planets in total: [[Ceres (dwarf planet)|Ceres]], [[Pluto]], [[Haumea (dwarf planet)|Haumea]], [[Makemake (dwarf planet)|Makemake]] and [[Eris (dwarf planet)|Eris]]. Moons orbit three of the dwarf planets. There are also thousands of [[Small Solar System body|small bodies]] in the scattered disc. As well as these, there are comets, [[Centaur (planetoid)|centaurs]] and there is cosmic dust.
== Discovery and exploration ==
For many thousands of years, people did not know about the Solar System. They thought Earth stayed still at the centre of the Universe and other things moved around it. People believed this until Nicolaus Copernicus<sup>(when?)</sup> made a mathematical model. His model said the Sun was at the centre of the Solar System. Most people did not believe him at first. But, in the 17th century, scientists such as Galileo, Kepler and Newton found out lots of physics. What they found out said Copernicus was right.
At first, people could only use their eyes to look at the Solar System. After telescopes were invented, scientists discovered much more of the Solar System. They found new moons and planets, and they could look at other things that they could not see before. More recently, scientists have sent spacecraft into the Solar System. The spacecraft discovered even more moons and features on other planets, such as mountains, craters, clouds, dust storms and ice caps.
== Structure ==
The main part of the Solar System is the Sun. It is a main sequence G2 star which contains 99.86 percent of the Solar System's mass. The largest four planets, the gas giants, make up 99 percent of the mass left.
Most large objects orbiting the Sun lie near the plane of Earth's orbit, called the ecliptic. The planets are very close to the ecliptic. However, comets and Kuiper belt objects are often at greater angles to it. The Sun, Mercury, Earth, Mars, Jupiter, Saturn and Neptune rotate anti-clockwise. Venus and Uranus rotate clockwise. All the planets and most other objects orbit the Sun anti-clockwise. There are some exceptions, such as Halley's comet.
The overall structure of the Solar System is divided into four regions: the Sun, the inner Solar System, the outer Solar System and the trans-Neptunian region. The inner Solar System is made of the four terrestrial planets and the main asteroid belt. The outer Solar System consists of the four gas giants. The trans-Neptunian region is made of all the objects beyond the orbit of Neptune.
Most of the planets in the Solar System are orbited by natural satellites (moons). These are large, ball-shaped bodies mainly made of rock. Most of the large natural satellites are in synchronous rotation. This means that one face of the natural satellite is always turned toward its parent planet. The four gas giants are orbited by planetary rings. These are bands of tiny particles and small rocks.
Kepler's laws of planetary motion explain how things go around the Sun. An object goes along an ellipse. The Sun is at one focus. Objects which are closer to the Sun go more quickly. This is because they are more affected by the Sun's gravity.
''to be continued…'' [[user:DJDunsie|<font color="red">DJ</font><font color="blue">Dunsie</font>]] ([[user_talk:DJDunsie|<font color="blue">talk</font>]]) 12:50, 13 June 2012 (UTC)
== Material to be used ==
In the Solar System often there is a Solar Wind. This is a flow of [[Plasma (physics)|Plasma]]. The Solar System is located in one of the arms of the Milky Way galaxy. The Milky Way galaxy contains about 200 billion (200,000,000,000) stars.
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