What are the Northern Lights?
Most of us know that awe-inspiring feeling standing watching a black night sky scattered with stars light up in rainbow colors during a fireworks display, yet this does not compare to Planet Earth’s rendition of magical light called Aurora. These unbelievably stunning displays can ordinarily be seen at the Northern and Southern Poles and are considered one of the natural wonders of the world. Over the Arctic they are called Aurora Borealis and over the Antarctic it is called Aurora Australis.
Contact encounters between gaseous particles in the atmosphere of the Earth and charged particles released from the atmosphere of the Sun result in the display of colors in the sky called the Northern Lights. The varying colors are as a result of specific types of gas particles that are bumping into each other. The scientific name for the Northern Lights are the Aurora Borealis.
The aurora effect starts on the surface of the sun with solar activity, injecting a cloud of gas, scientifically known as a coronal mass ejection (CME). This can take two to three days to reach Earth. When one of these ‘injections’ reaches earth, it collides with the magnetic field. The earth is surrounded by an invisible magnetic field, and were one to actually see what the shape is, the earth would appear as a comet with a magnetized extended ‘tail’ that stretches a million miles trailing behind the earth and in the opposite direction to the sun. As this coronal mass ejection collides with the magnetic field of the Earth, complex changes occur in the magnetic tail area generating currents of charged particles that flow along the lines of magnetic force directly into the Polar Areas. In the upper atmosphere of the Earth the particles are amplified and as they come into contact with oxygen and nitrogen atoms, they generate a radiant aurora panorama.
Knowing the resulting shape of a magnetic field in one of these coronal mass ejections stumps solar physics to this day as it is impossible to predict with any accuracy in which direction the CME field is pointing until the collision occurs, causing either an astonishing magnetic storm and stunning aurora or a fizzle. You may not always be able to see the Northern Lights, however, they are always there displaying their magnificence. Winter is the most favorable time to have a good sighting.
Aurora displays show up in a range of colors with pink and pale green as the most predominant colors. There have been reports of yellow, green, blue, shades of red and violet with the lights appearing in a multitude of forms such as patches, scattered clouds, arcs, shooting rays and pulsating curtains of light.
Although the Northern Lights may look like fire, if you were able to touch them, they would not feel like fire at all. It is true that the temperature in the upper atmosphere can reach thousands of degrees Fahrenheit, this heat is determined by the average speed of the molecules. The density of the air is extremely low at 96 Kilometers up, a thermometer would reveal temperatures way below zero in the location of an aurora display.
Auroras are sometimes difficult for the human eye to pick up however, with the use of a camera and a long-exposure setting plus a clear dark sky it is possible to obtain some remarkable and dazzling photographs. Sometimes an Aurora display can reach as high up as 1000 km although generally are between 80-120 km.
History indicates two people are credited with the naming of the Northern Lights. Pierre Gassendi named the Northern Lights between 1592 and 1655, after the Roman goddess of dawn; Aurora and the north wind; Boreas and Galileo Galilei between 1564 and 1642 with both of them bearing witness to a light display in September 1621. However, one of the oldest mentions of Aurora dates back to 2600 BC in China by the mother, of the Yellow Empire Shuan-Yuan, Fu-Pao who observed intense lightning making its way around a star called Su from the constellation of Bei-Dou, lighting up the entire area. Cro Magnon cave paintings have been discovered dating back to 30,000 BC and are considered to be one of the oldest depiction of aurora. A drawing of the Aurora with candles glowing above the clouds was discovered in 1570 AD. Another account of Northern Lights phenomena appears to have been found by the astronomers of King Nebuchadnezzar the second on a Babylonian clay tablet around 568/567 BC.
The closest space phenomena of the waxing and waning of aurora lights has enthralled humanity since prehistoric times and has resulted in the birth of mythological creatures, folklore as well as influencing religion, history and art.
Diverse cultures have their own explanations for this natural event, the Inuits of Alaska interpreted the lights as the souls of the animals they hunted. Menominee Indians from North America attributed the Aurora radiance belonging to the torches of the giants living in the North. The Europeans of the Middle Ages claimed the appearance of the glowing lights were a message from God. Others believed the lights to be those of opposing armies in heaven and perchance a sign of an imminent catastrophe. A singular appearance of the Aurora Borealis in the skies during the battle of Fredericksburg in 1862 convinced the rebel forces to believe that God was on their side.
For some cultures the appearance of the Aurora Borealis had more fearful and sinister connotations. Norse Mythology held the belief that the rays were the reflections of the Valkyries riding across the sky carrying slain warriors to a heroic resting place in Valhalla. The Inuit people held the belief that the Northern Lights were the souls of the dead involved in a disorderly game of primitive football. The Icelanders believed that a pregnant woman must avoid gazing at the Lights to prevent her child being born cross-eyed. The Northern Swedish Lapps feared the supernatural powers of the dazzling lights so either remained indoors chanting or if they were outside, they would cover themselves up to keep out of reach of the rays. The Alaskan Inuit kept their children hidden and even carried sharp knives for protection.
A little more about the Northern Lights
One of the most breathtaking recorded Aurora displays in recent history occurred in 28th August and the 2 September 1859 and is known as the “Great geomagnetic storm.”
There is a verb in the Icelandic language – “braga” – describing the movement of the Northern Lights.
A single medium sized sunspot coming from the plasma clouds would fit approximately 4 to 6 earths.
The Plasma speed collides with the stratosphere between 10.000 and 20.000 km per second.