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Note for parents: This learning resource for children follows the ‘I do, we do, you do’ teaching framework. For the ‘you do’ (independent practice) stage, you can download a free solar system question pack for your child here.
What is the solar system?
The solar system is a small part of the universe. The solar system consists of eight round planets that all orbit around the sun (the ‘solar’ star). Scientists think that the solar system formed about 4.7 billion years ago when a strong force we know as gravity pulled parts of a loose cloud of gas and dust together into clumps.
The sun is a large star at the centre of the solar system. At its core, the sun is 5 million degrees Celsius and is the source of all the heat and light that creates life on planet Earth. The sun has a very strong gravitational pull which pulls all the planets in the solar system towards it and keeps them in orbit.
As well as planets, the solar system consists of satellites and asteroids:
Satellites
A satellite is a moon, planet or machine that orbits a sun or a planet.
Artificial satellites are made by humans. They are machines which scientists send into space to perform specific tasks, such as taking weather forecasts.
Natural satellites are not made by humans. We also know them as moons – they travel around planets in nearly circular paths called orbits. Six of the eight planets in the solar system have at least one moon (only Mercury and Venus do not have any moons at all).
Asteroids
Asteroids are massive lumps of rock which float in space. There are millions of asteroids in a group called the Main Asteroid Belt between Mars and Jupiter.
I do: Download the following helpsheet to find out more about our solar system and the universe.
What planets are in the solar system?
There are eight major planets in the solar system. Here they are in order of distance from the sun (closest to furthest):
1. Mercury
Mercury is the closest planet to the sun and the smallest planet in the solar system (it's about as wide as the Atlantic Ocean!). Because it is so close to the sun, it only takes 88 days to complete a full orbit. Mercury is made entirely of rock.
The European Space Agency (ESA) has launched a mission called BepiColombo to investigate Mercury for the first time. The mission began in 2018 and is due to land on Mercury in 2025.
2. Venus
Venus is the second planet from the sun and the hottest planet in the solar system, with surface temperatures of 460 degrees Celsius (that’s 33 times hotter than Earth). It is also known as the evening or morning star because it is the second brightest object in the night sky after the moon.
Venus is about the same size as Earth and also has an atmosphere. However, the atmosphere on Venus is much thicker and cloudier than ours. Like Mercury, Venus is made from rock. It takes about 225 days for Venus to orbit the sun.
3. Earth
Earth is the third planet from the sun and our home. It is the only planet where we know for sure that animals and plants can live and survive because water takes a liquid form. Earth’s orbit around the sun takes 365 days, which we define as one year.
Earth has just one natural satellite – our moon.
4. Mars
Mars is the fourth planet from the sun and is often called the Red Planet because of its colour. It takes 687 days to orbit the sun.
Some scientists think that there might have been life on Mars millions of years ago because it has an atmosphere similar to Venus and Earth. There are lots of experiments trying to determine if life has ever existed there, including two rovers on the surface of Mars and six spacecraft orbiting it.
5. Jupiter
Jupiter is the fifth planet from the sun and the biggest planet in the solar system. It is over 1,000 times the size of Earth and is one of the four ‘gas giants’. It takes Jupiter 12 years to orbit the sun.
A storm on Jupiter called the ‘Great Red Spot’ has been blowing for at least 350 years. One spacecraft called Juno is currently orbiting Jupiter to try and find out how the planet formed and how the winds on it occur.
6. Saturn
Saturn is the sixth planet from the sun, the second largest planet, and the second of the gas giants. It’s very well-known for its rings, which are mostly made of ice. It takes Saturn 29 and a half years to orbit the sun.
7. Uranus
Uranus is the seventh planet from the sun and the coldest planet in the solar system, with surface temperatures of -220 degrees Celsius. For comparison, the coldest place on Earth is in Antarctica and is -94 degrees Celsius!
Uranus is the third of the four gas planets, and this planet’s particular gases make it appear blue. It takes Uranus 84 years to orbit the sun.
8. Neptune
Neptune is the eighth planet from the sun – the furthest in the solar system – and it was the most recent planet to be discovered (23rd September 1846).
Neptune is the fourth and final of the gas giants and also appears blue (like Uranus). It takes Neptune 165 years to orbit the sun.
We do: In the video below, the monster Ato is on an intergalactic adventure and needs to find a place to land his ship! Find out how we can use tables to work out where Ato can safely land.
10 facts about the solar system
People used to think there were nine planets in the solar system. But in 2006, the ninth planet Pluto was demoted to a dwarf planet because scientists decided it was too small to be defined as a normal planet.
The sun is 93 million miles from Earth. That’s the same as taking 5,000 return trips to Australia!
It takes light 8 minutes to travel from the sun to Earth.
Jupiter has a whopping 66 moons! The largest is called Ganymede and it's bigger than Mercury.
The sun isn’t the only star in the sky. There are hundreds of billions in the Milky Way (the galaxy we live in) – and 100 billion galaxies in the universe. That’s thousands of billions of stars!
The largest peak on Mars is a volcano called Olympus Mons, which is three times higher than Mount Everest.
The four inner planets (those closest to the sun) are known as terrestrial planets. They are smaller than the four outer planets (the gas planets) and are made mostly of rock.
The sun is so large that it makes up over 99% of the mass in our solar system.
You can often see Venus from Earth – clouds made of a gas called sulphur cover the entire planet, which makes it appear yellow in the night sky.
All of the planets in the solar system, except for Earth (which means ‘ground’), are named after Roman Gods:
Mercury: the fast-moving winged messenger
Venus: the goddess of beauty and love
Mars: the god of war
Jupiter: the king of the gods
Saturn: the god of agriculture
Uranus: the god of the sky
Neptune: the god of the sea
Test your knowledge
You do: Are you ready to have a go at some solar system questions?
Ask a parent or guardian to help you download our free question packs. You’ll be able to work through the questions independently and then mark them using our helpful answer guide!
Solar system glossary
Artificial satellite: a man-made object sent into space to measure things.
Asteroid: a large object made of rock and ice floating in space.
Atmosphere: the layers of gas which surround a planet. Earth’s atmosphere is mostly made up of nitrogen and oxygen.
Dwarf planet: a round space object which is smaller than a regular planet.
Galaxy: a large group of stars that all orbit around one central object.
Gas giants: four planets in the solar system which are made entirely of gas (Jupiter, Saturn, Uranus, and Neptune).
Gravity: the invisible force which keeps things in place. Gravity is the force which keeps moons orbiting around planets, and the planets orbiting around the sun.
Moon: a natural satellite which orbits a planet. Earth has the smallest number of moons (just one!) whereas Jupiter has 66 moons.
Natural satellite: a naturally-occurring object which orbits around a planet.
Orbit: the path that a moon takes around a planet, or a planet around the sun. Orbits are elliptical (meaning they are circular or oval-shaped paths).
Star: a massive ball of hot gas which gives off light and heat. The sun is the biggest star in our solar system.
Universe: the area which consists of everything that ever exists! It includes galaxies, stars, planets and everything else you can think of.
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