The short answer would be that the inclined axis of the Earth is in charge of causing the seasons. Throughout the year, different parts of the Earth receive the most direct rays from the sun. So when the North Pole tilts towards the sun, it is summer in the Northern Hemisphere. And when the South Pole leans towards the sun, it is winter in the Northern Hemisphere. That is to say … that it is the tilt of the Earth!
Many people believe that the Earth is closer to the sun during the summer, which is why it is warmer. Likewise, they think that the Earth is further from the sun in winter. But, although this idea makes sense, it is incorrect.
It is true that the orbit of the Earth is not a perfect circle , it is a bit uneven. During part of the year the Earth is closer to the sun than at other times. However, in the northern hemisphere we have winter when the Earth is closest to the sun and summer when it is further away. Compared to how far away the sun is, this change in distance from Earth during the year doesn’t make much of a difference in our climate.
What is the real reason for the seasons on Earth?
The axis of the Earth is an imaginary pole that runs through the center of the Earth from “top” to “bottom”. The Earth revolves around this pole making one complete revolution each day. This is why we have day and night and why every part of the Earth’s surface gets something from each.
Ultimately, the Earth has seasons because its axis does not rise straight . But what causes the Earth to tilt? Long, long ago, when the Earth was young, it is believed that something big hit it and knocked it out. So instead of turning with its axis up and down, it leaned a bit.
By the way, that big thing that hit the Earth is called Theia , which also made a big hole in the surface. That large impact sent a large amount of dust and debris into orbit. Most scientists think that this debris eventually became our Moon .
When the Earth orbits the sun, its inclined axis always points in the same direction. So throughout the year, different parts of the Earth receive direct rays from the sun.
We can say then that the tilt of the Earth is the reason for the seasons. The hemisphere that receives the direct rays of the sun has summer , while the hemisphere that leans away from the sun, thus obtaining its rays from a greater angle, has winter.
That is why sometimes the North Pole is inclined towards the sun (around June) and other times it is the South Pole that is inclined towards the sun (around December).
It is summer in June in the Northern Hemisphere because the sun’s rays hit that part of the Earth more directly than at any other time of the year. It is winter in December in the northern hemisphere, because that is when it is the turn of the South Pole to lean towards the sun.
