Why does northern hemisphere and Southern Hemisphere have opposite season?

The Northern and Southern Hemispheres experience opposite seasons due to the tilt of the Earth's axis, which is about 23.5 degrees. When the Northern Hemisphere is tilted toward the Sun, it receives more direct sunlight, resulting in warmer temperatures and summer. Conversely, during this time, the Southern Hemisphere is tilted away from the Sun, leading to cooler temperatures and winter. This axial tilt causes the seasonal changes as the Earth orbits the Sun.