Reasons for The Seasons

We love our boiling summers and our freezing winters, our defrosting springs and wet falls, but what causes these seasons?

Around 7 billion years ago, a large, Mars sized planet hit the new-born Earth with the power to knock it of its original axis. Now the Earth turns on a 23.5 degree angle. To be honest, we should be thankful for the hit, or else we would have a rainy season and a dry season. But how does getting hit with a large rock affect our Earth's systems?
During the summer (northern hemisphere) the axis of the Earth and the rotation around the sun, causes the northern hemisphere to lean closer to the sun. Likewise, when the Earth's axis and rotation causes the northern hemisphere to tilt further away from the sun, it becomes winter. This is because when it does tilt away, less sun hits the northern hemisphere directly. Same thing goes for when its summer, except its vise-versa. In the summer, more sun hits the northern hemisphere directly. This causes the seasons.

How did we find this out?
In science class we made a model of the system of the Sun and Earth, the Sun being a UV light while the Earth was a tennis-ball sized Styrofoam ball on a BBQ stick. We  proceeded by placing the Earth 30 cm away from the UV light. We then placed a see-through grid between the Earth and the light. Why the grid? To show how direct the light was hitting the Earth. The more curved the shadow of the grid lines on the sphere, the less direct the sunlight was. We then tilted the Earth at a 23.5 degree angle because of the asteroid and everything. Now you're probably thinking "Alex, how can you tell if the sphere is tilted when it doesn't have a side?" Well, we drew a line around the sphere representing the equator, and thus made a landmark to get an angle. We then proceeded with observations. We found that the light hit the Earth directly near the Equator no matter where the Earth was as it revolved around the Sun. However, the light didn't hit the Northern Hemisphere as direct when the Earth was leaning away from the sun; but the Southern Hemisphere was basking in the sun. On the other side, when the Northern Hemisphere was leaning towards the sun, the light was more direct. We then concluded that summer was when the Northern Hemisphere was leaning towards the sun and light hit it more direct. Winter was the opposite, when the light was less direct. Between was the spring and fall. When the sun hits the Northern Hemisphere the most/least, we get summer/winter solstice. When it's exactly in between the two solstices, it's known as an Equinox.

So next time your'e enjoying the summer weather or making snow angels, thank the large rock for hitting the Earth around 7 billion years ago.