Because charged particles cast off from the sun hit the Earth’s magnetic field 100 miles (160 km) up, making the air molecules glow green, violet, blue or red. These curtains of light are called auroras. The best spots to see the aurora borealis (or northern lights) are Alaska, the northwestern regions of Canada, the southern tips of Iceland and Greenland, Norway, and Siberia, The aurora australis of Southern Hemisphere is trickier to see unless you live in Antarctica.
Picture Credit : Google