Here's why:

* Earth's Tilt: The Earth is tilted on its axis at approximately 23.5 degrees. This tilt is the primary reason we have seasons.

* Summer in the Northern Hemisphere: When the North Pole is tilted towards the Sun, the Northern Hemisphere experiences summer. The days are longer, and the Sun's rays hit the Earth at a more direct angle, leading to warmer temperatures.

* Summer in the Southern Hemisphere: When the South Pole is tilted towards the Sun, the Southern Hemisphere experiences summer. This is the opposite of the Northern Hemisphere.

In short, when the South Pole is tilted towards the Sun, it's summer in the Southern Hemisphere and winter in the Northern Hemisphere.