Our Solar System

Our solar system is made of the Sun and everything that travels around it — including eight planets, their moons, dwarf planets, and many asteroids and comets. The whole system was born about 4.6 billion years ago from a giant spinning cloud of gas and dust.

The planets travel around the Sun in oval-shaped paths called orbits. The closer a planet is to the Sun, the faster it zooms around and the warmer it tends to be. The Sun's gravity is what holds every planet in its orbit, stopping them from drifting off into deep space.

The four planets closest to the Sun — Mercury, Venus, Earth, and Mars — are called the rocky planets because they have solid, stony surfaces you could stand on. They are smaller and denser than the planets further out.

The four far planets — Jupiter, Saturn, Uranus, and Neptune — are called the gas giants and ice giants. They are enormous balls of gas and ice with no solid ground to land on. If you tried to stand on Jupiter, you would simply sink through its swirling clouds.

Here is a surprise that catches many people out: Mercury is the closest planet to the Sun, but it is NOT the hottest. That title belongs to Venus, because Venus has a thick blanket of clouds that traps heat like a greenhouse, pushing temperatures hot enough to melt lead.

Far beyond Neptune is a ring of icy worlds called the Kuiper Belt. Tiny Pluto lives there. It used to be called the ninth planet, but in 2006 scientists decided it was too small and re-labelled it a 'dwarf planet'. It is still a fascinating little world with five moons of its own.