Red aurora borealis light and star trails. This trail of light is also known as the Northern Lights in the northern hemisphere. Early eskimos believed these lights were the playful souls of children on their way to heaven. Nowadays we know that the aurora occur when charged cosmic particles become trapped in the Earth's magnetic field. As the particles spiral toward the poles around the magnetic field lines, they collide with gas molecules in the upper atmosphere. This causes the molecules to ionize and form flickering patterns of light. Star trails are formed as the rotation of the Earth causes the stars to appear to move around the sky, centered on the celestial poles.