Auroras, also known as northern lights or southern lights, are visible in the polar regions and are caused by emissions of photons in the Earth's upper atmosphere from oxygen and nitrogen. Auroras form when charged particles from the sun enter the Earth's magnetic field, accelerating particles that collide with atmospheric gases and emit colorful glows. They typically appear as diffuse glows or curtains aligned with the Earth's magnetic field lines. Auroras have also been observed on other planets like Jupiter and Saturn.