These phenomena are seen at high latitudes such as the North and South Poles. The source of these auroras is the "solar wind" from the sun.
The solar wind refers to the electrons and protons that are ejected from the sun during the large explosions that sometimes occur on the sun's surface, and which come to the earth like wind. This solar wind stimulates atoms such as oxygen and nitrogen above the North and South Poles, causing them to emit light. This is what the aurora borealis is.
Why are auroras visible only in polar regions such as the North and South Poles? This has to do with the fact that the Earth is a large magnet with the S pole at the North Pole and the N pole at the South Pole.
Electrons and protons flying from the sun are attracted by the earth's magnet and fly toward the north and south poles. At this time, they stimulate the oxygen and nitrogen in the atmosphere above them, causing them to emit light.