Question

What is the single most important factor that determines why Earth (or almost any planet in the Solar System) experiences seasons?

Answer 1

Answer:

Planetary seasons are caused by two factors:

1. axial tilt and

2. variable distance from the sun

Explanation:

Earth's orbit is nearly circular and so has little effect on climate. It's our planet's axial tilt that causes almost all seasonal changes.

You can read further; Planetary seasons