When you are looking at pictures of the night sky, and it is all green, pink, and purple light, you may have wondered what the heck is happening up there. This beautiful light is known as the aurora borealis, or the northern lights, and it has generated myths and legends over the centuries. But it is not magic or wrathful deities. It all starts with our sun.

The sun is incessantly pushing bits and bits of itself into space. This flow of charged particles (primarily electrons and protons) is called the solar wind. It goes millions of miles and at last collides with the magnetic field of the earth. Luckily, though, that field serves as a sort of giant shield and most of the solar wind is repelled. However, the magnetic field is less near the North and South Poles. Part of those particles creep into the field lines and run away into our upper atmosphere.

When they arrive there, they hit gas molecules such as oxygen and nitrogen. The collisions transfer energy to the gas molecules and it is emitted as light. Consider it as a neon sign. Various types of gases produce various colors. The higher the altitude, the more the oxygen will result in red light, though in lower places, it will be green, the most prevalent color. Nitrogen gives off blues and purples. The entire affair is a gigantic light display, which is energized by the sun at ninety three million miles distant.

When then can you see this occur? and you must be very north or very south, where there is no city light. The most favorable locations in the north hemisphere include Alaska, north Canada, Iceland, Scandinavia and Russia. The season lasts late in August to early April since you need long and dark nights. The sky must be clear as well. No matter how bright the aurora is, clouds will destroy the sight. The lights are also strongest, in September and March, at the equinoxes. It is at that time that the solar wind will strike the earth at the appropriate angle.

You should also watch the solar activity. The sun has a period of eleven years, and during the peak, known as solar maximum, there are an increased number of sunspots and solar flares. It translates to increased solar winds and more frequent and intense auroras. And next few years we are going to one of such mountains, so it is a good time to plan a trip.

Finally, the aurora borealis is a lesson that the world is not alone. It is in a continual dance with the sun, particles and magnetic fields. And in case you are ever lucky enough to be under a curtain of rippling green light, keep in mind that you are observing the solar wind greeting the upper atmosphere. A cool thought that is.