Question

Why is it summer in the northern hemisphere when it is winter in the southern hemisphere?

Answer 1

In short, it's because of the tilt of the earth in relation to its poles.

Explanation:

The earth is tilted in relation to its poles, leaving half of it closer to the sun than the other at any one time. When it's winter, it's because the spot where you live is facing away from the sun, meaning the other half is facing towards it, thus, they have summer.