Aurora Borealis over Earth, taken from the International Space Station. City lights are seen on the surface below the aurora. The brightest patch just left of lower centre is Helsinki, in Finland. To its right is Talinn in Estonia. The lower bright patch at bottom left is Turku in Finland, and St Petersburg in Russia is at lower right. The aurora borealis (Northern Lights) is a glow caused by charged particles in the solar wind interacting with gases in the atmosphere. The charged particles energise the gases, which emit light when they release the energy. Aurorae typically form at altitudes above 80 kilometres. The ISS orbits some 380 kilometres up. Photographed during Expedition 6 (24th November 2002 to 4th May 2003).