How do we know which sunspots will cause bright auroras on Earth?
In order for a sunspot to generate auroras on Earth, the solar wind it releases must be pointed in the general direction of Earth. A newly formed sunspot near the middle of the solar disc provides an early warning that a fast-moving burst of charged particles is heading in our direction. As they reach Earth’s magnetic field and penetrate into the atmosphere, intense auroras begin to surge across the sky.
