Sun and Earth. Illustration of the Sun and Earth, showing surface detail on the Sun and the aurora borealis (northern lights) around Earth's North Pole. The granular appearance of the Sun's surface is caused by continuous turbulence driven by the massive nuclear fusion reactor in the core. The dark sunspots are areas of relative coolness. The loop-shaped solar prominences are eruptions of plasma (super-heated charged particles) confined within tube-shaped magnetic fields. The aurora is a pattern of coloured light seen in the night sky near the poles. It occurs when charged particles from the Sun are trapped in Earth's magnetic field and collide with gas molecules in the atmosphere.