Planets of the Solar System
This page provides a brief description of each of the planets (and links to dwarf planets) of our solar system. You can also find out about the difference between planets, dwarf planets and small solar system bodies (SSSBs) here.
Solar System Map - showing size, mass and orbital period, and orbit scale of planets & dwarf planets
Available as a poster here.
The Planets of the Solar System
The planets and the solar system were formed from a huge cloud of gases and dust particles left over when a massive star exploded as a supernova.
The gas drifted in space and it's thought that another supernova explosion nearby may have caused a pressure wave to pass through the cloud that caused clumping to coccur. As the matter clumped together, gravity in that area got stronger which attracted more matter which in turn increased the gravitational pull. As more and more matter fell toward the high density area, due to conservation of momentum it began to spin - rather like water going down a plug hole. The result was that as the gravity intensified, the spin became faster resulting in a flat disk of gas and dust surrounding a central high density sphere of gas.
Gravity was also working within the disk of rotating gas and dust pulling matter together to form primitive planets within the gas disk.
Eventually the temperature and pressures in the central sphere became so high that the atoms began fusing together (nuclear fusion) and the Sun ignited producing heat and light and also the solar wind - an outstreaming of subatomic particles.
The heat of the Sun and the solar wind immediately began to have an effect on the huge cloud of gas and particles in the disk. Volatile substances such as water ice near the Sun would heat and sublimate into gas, and these and other gases such as hydrogen would be gently accelerated away from the Sun by the solar wind.
At the distance of Jupiter, the temperature the Sun was not high enough to cause water ice to evaporate and so this meant that large quantities of solid material were available to build larger planets. These planets could therefore attract and keep hold of more of gas from the gas disk. This is one theory as to why the gas giants became so large, and why there is a divide in planet size between the small inner rocky planets and the outer gas giants.
As time continued, the workings of gravity and the solar wind eventually resulted in the solar system becoming as we know it today. A mostly empty space with eight surviving planets, five dwarf planets, a band of possibly millions of asteroids. All of this is thought to be surrounded by a cloud of icy comets - preserved remains of that early dust from which the solar system formed.
Planets and Dwarf Planets in Order from the Sun
The planets and dwarf planets are listed here in the order they are from the Sun. Click for more information on each.