Imagine you are outside at night. You look up at the dark sky and see a curtain of lights dancing across the sky. What could it be? What is causing it?

You have just observed the phenomenon known as the Northern Lights.

This type of phenomenon has several names, such as Aurora Borealis (Northern Lights), Aurora Australis (Southern Lights) and Aurora Polaris (both Northern and Southern Lights). The name Aurora Borealis is Latin for “red dawn of the north.” The famous scientist Galileo Galilei gave the Northern Lights their scientific name.

The auroras originate from the sun, where enormous explosions and flares called coronal mass ejections occur. A result of these explosions is that large amounts of solar particles called plasma clouds are released into space. These clouds travel at speeds from 300 to 1,000 kilometers (approximately 186.4 to 621.4 miles) per second! However, even at such incredible speeds, it still takes the clouds two to three days to reach Earth.

Once they are close to Earth, the clouds are captured by the planet’s magnetosphere, which is the magnetic field outside the atmosphere. The magnetosphere guides these clouds to the geomagnetic North and South Poles. As the clouds are en route to the poles, they are stopped by the atmosphere, which acts as a protective shield against these deadly solar particles.

The solar particles collide with atmospheric gases, producing photons (a light particle), and resulting in an aurora. However, in order for someone to see the aurora without the aid of a telescope, there would have to be approximately 100 million photons produced.

What causes the sun to release plasma clouds? The sun’s surface contains areas of strong magnetic fields called sunspots. These areas are approximately 1,000 degrees cooler than the rest of the surface of the sun, which is estimated to be between 5,800 and 6,000 Kelvin (around 9,980.6 to 10,340.3 degrees Fahrenheit). This results in the sunspots being darker than the rest of the sun. The sunspots are noticeable signs of the process that sends plasma clouds into space, in turn creating auroras on earth. The number of sunspots on the sun varies over a time cycle of approximately 11 years. A solar maximum is when the peak of sunspots is reached, and a solar minimum is when the number of sunspots is at its low point. Obviously, the more sunspots that are released, the more auroras occur on earth.

Are the auroras all the same shape and color? The answer is no. The color depends on the altitude of the aurora, which is between 100 and 120 kilometers (62.1 to 74.6 miles) on average. An aurora can be blue or violet, which appears below 120 kilometers (74.6 miles); green, which occurs at 120 to 180 kilometers (74.6 to 111.8 miles); or red, which originates at higher altitudes. However, red can occur at 90 to 100 kilometers (55.9 to 62.1 miles) when the sun is “stormy.” Also, entirely red Northern Lights are occasionally seen; however, this happens generally at lower latitudes.

People often mistake the Northern Lights for a fire on the horizon. Auroras come in various shapes or patterns. The appearance of the different patterns depends on the solar activity—solar maximums and solar minimums.

How bright are auroras? The brightness of auroras is less intense compared to the sun and moon. However, there are varying degrees of strength—weak, medium and strong. The weak Northern Lights can be compared to the Milky Way. The medium strength has a tendency to be brighter than most stars. The strong Northern Lights are compared to the light of the moon, much stronger than the light from stars.

How and where can Northern Lights be seen? The ability to view Northern Lights depends on whether you are located within the aurora oval. The aurora oval is where auroras with great intensity occur. The most common places are the northern parts of Alaska, Russia and the Nordic countries, which includes Greenland and Svalbard. One to two times per decade, the Northern Lights can also be seen in the mid to northern areas of Canada, as well as in Mexico and various Mediterranean countries.

The Northern Lights are most visible during late September to late March. They do not constantly occur, however, which makes them somewhat challenging to see for those who travel to the aurora oval. But patience will likely be rewarded with a spectacular sight!

The Northern Lights are a truly awesome phenomenon, and are just one more example of the majestic beauty of God’s creation!

Source: www.northern-lights.no