Why do aurora borealis and aurora australis occur?

Aurora borealis and aurora australis occur due to the interaction between solar wind—charged particles emitted by the sun—and the Earth's magnetic field and atmosphere. When these charged particles collide with gases in the Earth's atmosphere, they excite the gas molecules, causing them to emit light. This phenomenon typically occurs near the polar regions, where the magnetic field lines converge, creating vibrant displays of color in the night sky.