Why do we do experiments?

Ok, so I don't know too much, but here's what I've got so far... A reason why we have those seasons is because the Earth tilts on its axis in an orbit around the sun. So, because of this, one part of Earth is more exposed to sunlight than the other side. When the Earth revolves around the sun, different parts of the Earth are hit by the sunlight. Since this is occurring, the Southern Hemisphere experiences a different season than the northern hemisphere. I hope that helps!!