Course Learning

The Solar System is the name given to the part of space that surrounds the Sun.

Even though it is bigger than anything we can imagine, the Solar System is actually a very tiny part of the universe.

The Solar System is made up billions of objects, including planets, moons, asteroids and comets that are all held in the Solar System by the gravitational pull of the Sun which sits right at the centre.

• The Sun is a star. It is a big ball of the gases hydrogen and helium and makes its own energy from nuclear fusion.
• You wouldn't be able to stand on any of the gas planets, that's because Jupiter, Saturn, Uranus and Neptune don’t have solid surfaces, although they do have a rocky core.

• Saturn's rings are made of 90% water.
• It only takes Mercury three Earth months to orbit the Sun.

• The Solar System is roughly 4.5 billion years old.
• The whole of Mars is as cold as our South Pole.
• There are more stars in the Universe than there are grains of sand on all of our beaches on Earth.
• The Great Red Spot is a storm twice as wide as Earth, and has been observed on Jupiter for more than 300 years.

There are four rocky planets in our Solar System, these are:

• Mercury
• Venus
• Earth
• Mars.

They are the closest planets to the Sun. They each have moons but are smaller than the gas planets.

There are also four gas planets, these are:

• Jupiter
• Saturn
• Uranus
• Neptune.

These are the farthest planets from the Sun. They each have many moons and they are much bigger than the rocky planets.

Until 2006, there were nine planets that made up our Solar System: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune and Pluto.

Pluto was furthest from the Sun and smaller than any of the other planets.

After more research and after comparing it to other objects in the Solar System, it was decided to reclassify Pluto as a dwarf planet.

So whilst it is still in the same place in the Solar System, Pluto is no longer counted as one of the main planets.