View of the aurora borealis (northern lights), moon, and scattered light pollution of nearby city of Tromso (the red-yellow glow at left) in northern Norway. Stars of the Big Dipper (prominent part of the Ursa Major) are visible through the aurora arc in the upper left. The aurora borealis is a coloured light display that is visible in the night sky at high latitudes. It occurs when charged and energetic particles from the Sun (the solar wind) are drawn by Earth's magnetic field to the polar regions. Hundreds of kilometres up, they collide with gas molecules and atoms, causing them to emit light.