By Chris Skeldon 
Classified as a natural, optical phenomenon, the aurora borealis only exists thanks to the sun. In addition to heat and light, the star sends a lot of energy and various molecules to the Earth, from which its magnetic field protects it.
When streams of these highly energetic particles, known as the solar wind, pass around the magnetosphere, aurorae occur. The planet's magnetic field protects us from cosmic radiation, but the shield is naturally weaker at the north and south poles, allowing solar winds to slip through the atmosphere – generally 100 to 300 kilometers above the Earth's surface.
When solar particles pass through the atmosphere, they heat up the gases, which then glow vibrantly in the night sky. So what we see in the sky are millions of individual collisions that follow the Earth's magnetic field lines.
Twilight generally appears green, Because the oxygen atoms available in the part of the atmosphere that the solar wind reaches emit this tone.
The duration and appearance of the aurora are unpredictable. It can last a few minutes or hours. The best places to enjoy the Northern Lights range from Alaska to Iceland, through Canada, Greenland, Denmark, Sweden, Norway, Finland and even points north in the USA.
In the beliefs of the ancient Norse people, the aurora borealis was a harbinger of war and therefore frightened everyone whenever it appeared. Centuries ago, it was linked to spirit activities and the dancing lights in the sky were called “giant arctic foxes.” However, nowadays, this luminous spectacle fascinates many tourists, who travel to the Arctic region just to “hunt” for the Northern Lights.