ELi5: If seasons are due to the tilt of the earth and not the orbit around the sun, how do they occur on roughly the same days every year?

Question

Is it just coincidence that the 4 season begin and end at same point in the orbit around the sun?

In: Physics

Answer 1

It’s both the tilt and the orbit. The earth has the same tilt throughout its orbit. During winter on the northern hemisphere it is splinter on the Southern Hemisphere because the tilt is such that the Southern Hemisphere is less angled with respect to the sun. The bigger the angle with respect to the sun, the more the sunlight is spread over the surface of the earth. The more spread, less heat, while more concentrated means more heat. When the earth complete half it’s orbit, such that the tilt makes it so that it is summer in the northern hemisphere and winter in the Southern Hemisphere.

The reason you are probably thinking it is only the tilt is you probably heard someone say the distance to the sun doesn’t matter and in the context of a single planet in an unchanging orbit, the only possible source for a change in distance is due to the orbit (orbits can be elliptical), so the person probably mentioned orbit