THE SOLAR SYSTEM
AN INTRODUCTION...
In our solar system, nine planets circle around our Sun.
Mercury
Venus
Earth
Mars
Jupiter
Saturn
Uranus
Neptune
Pluto

 
The Sun sits in the middle while the planets travel in circular paths (called orbits) around it. 
These nine planets travel in the same direction (counter- clockwise).
The Sun is the heaviest, largest, and hottest body in the Solar System.
The solar system is made up of two parts:
  • The INNER SOLAR SYSTEM contains Mercury, Venus, Earth and Mars. These four planets are closest to the Sun.
  • The OUTER SOLAR SYSTEM contains Jupiter, Saturn, Uranus, Neptune and Pluto.
The inner planets are separated from the outer planets by the Asteroid Belt
COMPOSITION
  •  ROCKY PLANETS (Mercury - Venus - Earth - Mars - Pluto)
The rocky planets are mostly made up of rock and metal. These planets are very heavy and move slowly. They also do not have rings and very few moons.
  •  
  • GAS PLANETS (Jupiter - Saturn - Uranus - Neptune)
The gas planets are mostly made up of gases (hydrogen and helium). These planets are light for their sizes (just like a big air balloon) and move quickly. They have rings and lots of moons
SIZE
  • SMALL PLANETS (Mercury - Venus - Earth - Mars - Pluto)
The small planets have diameters less than 13000 km across. Mercury and Pluto are the smallest planets.
  • GIANT PLANETS (Jupiter - Saturn - Uranus - Neptune)
The giant planets have diameters greater than 48000 kilometres. The giant planets are also called gas giants
MOVEMENTS
Each of the nine planets has two ways of moving.
  • Every planet spins, or ROTATES, on its own axis.
The time it takes for a planet to rotate is known as a "day". Since the Earth spins on its axis every 24 hours, OUR day is 24 hours long. A day on Jupiter is the shortest - a little less than 10 hours. However, the planet Venus travels very slowly. One day on Venus would last for 243 of our Earth days!
  • The planets also revolve around the Sun. The path that each planet follows around the Sun is called its ORBIT.
The time needed for a planet to make one trip around the Sun is called a "year". You know that a year on Earth is about 365 and one-fourth days. Since Pluto's orbit is so far from the Sun, its year lasts for 247 of our years.

 
OTHER COMPONENTS OF THE SOLAR SYSTEM
Besides the planets, there are countless smaller bodies that are part of our Solar System.
  • ASTEROIDS, which are minor planets.
  • COMETS, which are frozen balls of ice
  • METEORS, which are solid particles