Why can't it always be summer?

There's a reason why Earth has seasons — and it's about being totally tilted.

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With its long days just itching to be spent by water doing nothing, summer really can be an enchanting season. Sadly, all good things must come to an end — summer cannot last for ever. Why not? Well, there's both a simple reason and a more complicated one.

The simple reason is that it can’t always be summer because the planet is tilted. The more complicated answer requires some geometry.

Earth's orbit and the seasons

First, you need to know that Earth is a sphere. Technically, it has an oblate spheroid shape. That means that the planet is shaped like a satsuma — a little bit wider than itis tall. Earth travels through space in an orbit around the Sun. Its orbit is an ellipse — which is more like an oval than a circle —so there are times when Earth is closer to the Sun and times when it's further away. A lot of people assume this distance is why we have seasons, but they are not right. In the UK, the Earth is three million miles closer to the Sun during winter than in the summer.

Spinning like a top