ScienceOur solar system
The sun, its eight planets in order, and what makes the earth just right for life.
The solar system is our neighbourhood in space. It is made up of the sun and everything that travels around it: eight planets, their moons, dwarf planets such as Pluto, and smaller bodies such as asteroids and comets.
The sun
The sun is a star, a huge ball of very hot, glowing gases. It is by far the biggest object in the solar system. Its pull, called gravity, keeps all the planets moving around it. The sun gives us light and heat, and without it there would be no life on earth. Never look at the sun directly; it can damage your eyes.
The eight planets
A planet is a large body that moves around the sun in a fixed path called an orbit. Planets have no light of their own; they shine because they reflect sunlight. In order from the sun, the planets are:
- Mercury: the smallest planet and the nearest to the sun.
- Venus: the hottest planet, wrapped in thick clouds. It is the brightest planet in our sky and is called the morning star or evening star.
- Earth: our home, the only planet known to have life. From space it looks blue because of its oceans.
- Mars: the red planet. Its soil is rich in rust-coloured iron.
- Jupiter: the largest planet, a giant ball of gas with a famous Great Red Spot, which is a storm.
- Saturn: known for its beautiful rings, made of ice and rock.
- Uranus: an icy, blue-green planet that spins tilted on its side.
- Neptune: the farthest planet, cold, blue and windy.
A sentence to remember the order: My Very Eager Mother Just Served Us Noodles.
The first four planets are small and rocky. The last four are much bigger and are made mostly of gas and ice.
Moons and other members
A moon, or natural satellite, is a body that moves around a planet. The earth has one moon. Some planets have many. Between Mars and Jupiter lies a belt of rocky pieces called asteroids. Comets are balls of ice and dust that grow a glowing tail when they come near the sun. Pluto was once counted as the ninth planet; since 2006 it has been called a dwarf planet.
Why earth is special
The earth is at the right distance from the sun: not too hot, not too cold. It has liquid water, air with oxygen, and a layer of gases that shields us from harmful rays. So far, no other planet is known to have life.
Key terms
- Star
- a huge ball of hot, glowing gas that gives out its own light
- Planet
- a large body that moves around a star
- Orbit
- the fixed path of a planet or moon
- Satellite
- a body that moves around a planet
- Gravity
- the pull that holds planets in their orbits
Try it yourself
On a clear evening, look at the western sky just after sunset, or the eastern sky before sunrise. The brightest "star" that does not twinkle is very likely the planet Venus. Planets shine steadily; stars twinkle.
Quick questions
Answer in your head or on paper first, then tap to check.
How many planets are there in the solar system?
Eight.
Which planet is the largest, and which is the nearest to the sun?
Jupiter is the largest; Mercury is the nearest.
Why does a planet shine?
It reflects the light of the sun; it has no light of its own.
Why is life possible on earth?
It has the right temperature, liquid water and air with oxygen.
This is a simple explanation to help you understand. For examinations, read the same chapter in your prescribed textbook. Last checked: 11 November 2026.