Nature has many marvels to behold, one must see at the top of the bucket list for anyone is the northern lights. The northern lights are also known as the Aurora borealis in the northern hemisphere or Aurora australis in the southern hemisphere.
The aurora displays are most visible during the cold clear nights found close to the North and South poles. Aurora displays are visible at all times of the year and on very rare occasions during the day. Aurora borealis displays are most often visible during the fall and winter months.
The area of highest visibility is located in an oval shaped area running from Alaska to Greenland. It is possible to view the Aurora borealis as far south as Toronto and even New Orleans during times of peak activity, but usually they are only visible close to the poles. In the southern hemisphere it is even rarer to see a display as the Aurora australis is only visible in Antarctica and the oceans that surround it.
Aurora borealis is caused by charged particles that are thrown off the sun as it spins. These particles travel through space and collide with gaseous particles in Earth’s atmosphere. When the two types of particles collide they create the fantastic colours that make up the displays.
The most common colour is neon green which is caused by charged particles hitting oxygen particles about 50 km above the Earth. Blue and purple displays are caused by the collision of charged particles hitting nitrogen particles in the atmosphere and red displays are the result of charged particles hitting oxygen particles 200 km above Earth’s surface. The actual displays start about 60 km above Earth’s surface and can continue up to at least 600 km above the surface.
The magnetic field surrounding Earth deflects many of the particles as our planet passes through the vast cloud of charged particles thrown off by the sun. Since the magnetic field differs at the poles more of the charged particles can get through which is why the Auroras are strongest at the North and South poles. Other planets can experience Auroras as well.
The Aurora Borealis and Aurora Australis both happen at the same time. When one pole is experiencing a display it is mirrored on the other side of Earth. This helps to put in perspective the size of the cloud of charged particles that the sun spins off and that is carried here on solar wind. Aurora borealis peaks in intensity roughly every 11 years making 2013 a peak year. The next peak year will be in 2024.
There are many different legends that surround the northern lights. In medieval times Aurora borealis was considered a sign that war or famine was on the way. Early settlers in both Europe and New Zealand thought the lights to be the reflection of campfires. Many aboriginal first nations’ people in North America believed the northern lights to be the spirits of their people.
The next time you are out at night in the fall or winter, look North for the northern lights. Many tour companies offer Aurora borealis packages, so if you are taking a cruise to Alaska or plan to visit the Yukon and Canada’s far north try to book your trip at a time of the year when the display will be at its best. Aurora borealis’ eerie yet magical light show is a show that is not to be missed.
Copyright 2019 Mike Wilson
