This is a misconception that tons and tons of people have, though very few of them think about it.
What causes the seasons?
This appears to be a fairly simple question. The most intuitive answer, and the one that most of us harbor from a young age, is that the Earth is closer to the Sun in the summer, and farther in the winter.
Think about it, though. In June, when it’s summer in the Northern Hemisphere, it’s winter in the Southern Hemisphere. That doesn’t fit with our quick explanation. So let’s go a little deeper.
The Earth has an orbital radius of between 90 and 96 million miles; that 6 million miles of variance is insignificant, and couldn’t cause seasons. Also, most of us have heard at one time or another that Earth’s poles have multiple months of near-constant darkness or light, and this causes the seasons there to be extreme.
So, how about this?
The hemisphere in question experiences winter when it is tilted farther from the Sun; when this happens, the sun’s rays hit the Earth at a more oblique angle, and so their energy is more spread out. By contrast, when the hemisphere is tilted towards the Sun, the rays hit it nearly head on, with full power; this causes summer.
This is also why the tropics experience few changes with the seasons. These regions are close enough to the equator that the Earth’s tilt does not affect them very much.