The light spreads on the earth unevenly due to It's tilt. The position
of the earth changes in orbit, and the earth either becomes tilted
towards or away from the sun. This is why seasons happen.
Here're the reasons;
1)The right neighbours.
2)The right core.
3) The right star.
4) The right moon.
5) The right crust.
6) The right ingredients.
7) The temperature and ingredients.
Rover was the type of space probe designed to move around on the surface of a Moon or Planet.
The Hindu-Kush mountains also border tibet.