There is an imaginary line that passes through the Earth from the North Pole to the South Pole. This is the Earth's axis. This axis is not straight up and down - it is slightly tilted (slanted). The tilt is about 23.4 degrees and is always in the same basic direction.
The Earth spins on this axis. It takes 24 hours, or one day, to spin right round once. When one side of the Earth faces the Sun it is daytime there. When it faces away from the Sun it is night.
Click on the button on the left to see the Earth spin on its axis.
So, now we know that the Earth orbits the Sun while it spins on an axis that is tilted. The tilt is always in the same basic direction.
Therefore, as the Earth orbits the Sun on its tilted axis, different hemispheres face the Sun at different times. We can see from this diagram which hemisphere is tilted towards the Sun depends on what time of year it is on Earth.
Now we will find out how this tilt causes the seasons.
Remembering what you have learnt so far try this quiz question. Don't worry if you get it wrong - we'll explain the answers.
In Britain we have Summer because....