Why do seasons change?

Many people think summer happens when the Earth is closer to the Sun. It is not. The Earth is actually slightly closer in January.

The real reason is a tilt. The Earth leans over by about 23 degrees as it travels around the Sun. For half the year the northern half leans towards the Sun — longer days, stronger sunlight, summer. For the other half it leans away — shorter days, weaker light, winter.

Because the halves are opposite, when India has summer, Australia has winter.

Near the equator, including Kerala, the tilt changes very little, so there is no true winter — just hot, hotter and rainy. The monsoon is Kerala’s real season change.