The Solar System
The Big Idea
The big idea of the Solar System is that the Sun is at the centre, orbited by the planets and other objects. Some planets have moons which orbit them.
Key questions
Why does Neptune take the longest to travel around the Sun?
It takes the longest because it has the furthest distance to travel and because it has the slowest speed of all of the planets.
What is the difference between rotating and orbiting?
An orbit is the path an object travels through space (e.g. the Earth orbits the Sun. All objects in space rotate - they spin on their own axis. Some spin quickly and some spin very slowly.
What evidence is there that the Sun is at the centre of the solar system?
Galileo found two key pieces of evidence using his telescope.
He saw moons orbiting Jupiter, which shows that smaller objects orbit bigger ones.
He saw the phases of Venus (it is a crescent sometimes and a full circle at other times). This happens because Venus orbits the Sun.
If we look at the sky, how can we tell if a bright object is a star or a planet?
If you take a photograph of the sky several days apart and then overlap the two photographs so that all of the stars line up, you might see that one bright object has moved. This will be a planet.
Common misconceptions
The Sun is not a star. (The Sun is a star - and quite an ordinary one too).
The Solar System only includes the Sun, planets, and our Moon. (There are many other objects in our Solar System, including asteroids, planetoids (like Pluto), comets as well as the space probes humans have sent out.
Planets cannot be seen without a telescope. (Jupiter and Venus are easy to see with our bare eyes. Mars and Saturn can also be seen unaided. Mercury is always close to the Sun, so it is harder to see, but it is possible. The others need a telescope to see them).
Gas giants are large balls of gas, which a spaceship could fly through. (Sadly not - most of them have a solid core deep below the surface. Even if they didn’t, the pressure would be so high, any spaceship would be crushed).
All planets have rocky surfaces. (Only the inner planets have rocky surfaces).
The seasons are caused because the Earth is closer to the Sun in the summer. (This is similar to the misconception that the equator is warmer because it it closer to the Sun. The reason for both effects is the angle the Sun’s beams fall on the Earth’s surface.)
Progression
EYFS
Know that there are stars and planets in space. Know that you need a rocket to get into space. Know that you need a rocket to move from one planet to another.
KS1
Know that you need a special suit to survive in space. Know that people and robots can travel through space using rockets. Know that people have been to the Moon, but only robots have been to other planets.
LKS2
Use a Solar System model to show how planets orbit the Sun and how moons orbit their planets. They should know that the Sun is a star.
UKS2
Understand that the Solar System model is not to scale - the planets are too small and the distances too big to make a convenient model. They should know that the closer the planet is to the Sun, the faster it travels.
Pupils should be able to use a globe to explain day and night using the rotation of the Earth and be able to explain why the Sun appears to move across the sky over the course of a day.
KS3
Pupils will learn that gravity is the force which causes planets to orbit the Sun and moons their planets (without gravity, the planets would travel off into space in straight lines). They will calculate the weight of objects on different planets. They will learn about galaxies. They will finally learn about the role of the Earth’s tilt in the seasons.