Astronomical presentations can delight onlookers and create a sense of awe in those who witness these elaborate displays. Whether lying underneath the stars or traveling to the far reaches of the earth, the pure magnitude of what is above never fails to prove the effort worthwhile. One such astronomical phenomenon is the Northern Lights which is scientifically referred to as aurora borealis. This magnificent display has been the foundation of mythological epics in ancient societies and led to the inquiry as to the earth’s relationship with the solar system beyond its atmosphere (Brekke & Egeland, 1994). Having brought together myths and spectators, alike, understanding the astronomical causes of the display has branched to a greater understanding of the earth’s atmosphere, the effects of the sun on the earth, and methods to anticipate potential interferences with modern society. Although many of the earlier claims have been disproven, it is the evolution of research and knowledge that lays the groundwork for future study. In order to expand on this evolution of knowledge that has occurred without dismissing the awe of the spectacle, this paper will present the science behind the northern lights as evolved since the earliest documented observations.
Early Sightings and Explanations
Early sky watchers looked to the heavens to gain a better perspective as to the meaning of life and the place of the earth in the greater universe. According to Watson (2013) the name, aurora borealis, came from a French artist, Pierre Gassendi, after Roman mythology. Aurora comes from the goddess of the dawn and borealis comes from the god of the northern wind. Watson (2013) goes on to explain that the Vikings began to explain in the 1250s that the lights were not a symbol of mythological gods but rather based in scientific interactions that could be explained by a deeper understanding of the earth. In the book, The King’s Mirror, the Vikings referred to the cause of these lights as being the result of the power in the frost and glaciers. While this theory was later proven to be incorrect, it is notable that this began the scientific discussion of the northern lights.
As with most scientific discoveries, this discussion began with the marvel of the observation and led to disagreement and areas of consensus to guide the inquiry towards evidence and its application. Many centuries later, the northern lights fell into the discussion of chemistry as new advancements in this area of science were being presented. According to Kragh (2010) this created a significant disagreement as to the interactions with either nitrogen or oxygen being the catalyst for the light show. Understanding the relationship between low pressures and the atmospheres, the 1870s directed scientist to focus on the green line of the aurora and attempt to recreate the display in laboratory settings with known chemical compounds. Continuing to investigate the both known and unknown chemical compounds, it was not until the 1920s auroral spectroscopy recognized the gases in crystalline dust due to temperature differences and a true understanding of the spectrum of space became possible (Kragh, 2010).
Recognizing the Skies
Prior to the discoveries in chemistry being accepted as an area of consideration, Kristian Birkeland presented the phenomenon of the northern lights in the context of atmospherically relevant phenomenon rather than earth based variations. According to Watson (2013) the researcher presented the theory that auroral electrojets connect to currents which move along geomagnetic lines which run from the magnetosphere away from the polar region to the high latitude ionosphere. Although the currents were eventually named after this the scientist, Watson (2013) notes that his theories were highly controversial for the time which meant that it was not proven to be true until 1967 which was years after his death.
Despite not having had the acceptance of the scientific community during his lifetime, Birkeland is responsible for a great number of discoveries relating to both the northern lights and other areas of astronomical knowledge. According to Brekke and Egeland (1994) this knowledge expands to the connectivity between the earth and sun as well as how this connection alters the atmospheric weather and creates displays of aurora. In fact, Watson (2013) adds that the theory presented by Birkeland developed the actualization of how the phenomenon is create and how it affects the earth. Simply put, the northern lights are created by hundreds of millions of solar particles that are in the solar winds. Electrically charged, these particles could create extensive damage to the earth if the atmospheric shield was not in place. Instead, the particles collide with the shield and photons or light particles. Watson (2013) goes on to explain that the display shimmers as a result of one explosion fading as another particle reaches the shield. The colors, such as the most commonly studied green lights of the display, are the result of the height at the point of the collision and the gases that are in the atmosphere. Both factors are essential for determining the coloration with the same gases at different heights producing different colors of the lights (Watson, 2013).
Beyond Earth
While the northern lights are a phenomenon on earth, it is important to note that astronomers have discovered other auroras that occur at the atmospheric edge of other planets making the position of the sun and presence of chemical compounds increasingly relevant to all areas of this field of science. For instance, Watson (2013) explains that the Jovian Aurora is found on Jupiter due to the same response of the particles and the atmospheric shield. The auroras are found at the poles in the same way as occurs on earth making the contributions of the magnetic fields increasingly evident. In 2008, the same phenomenon was discovered on Saturn creating a deeper understanding as to the northward and southward directives of the planet rotations across the solar system (Watson, 2013).
Current Research
One of the greatest drivers of ongoing research, especially in astronomy, is the advancements that allow the scientists to get ever closer to the phenomenon in question. Although looking at the northern lights from the ground level continues to bring awe to the general onlooker, the ability to view the phenomenon at a closer level has brought additional knowledge about the role of electrons and the power of the solar winds. According to Heavisides (2015) research is ongoing to place sensors along the magnetic fields which has led to multiple conclusions about the aurora. For instance, it is now known that the temperature blast from the collision changes the chemicals from gas to a form of plasma along the atmosphere. Within this plasma, the electrons move about in what Heavisides (2015) compares to a pattern similar to what is found in the wiring of a home. However, the researcher also notes that the exact movement is not yet known and therefore it remains a mystery as to how the sun affects the magnetic field protecting the earth.
Notably, it is in these possible effects that the scientists continue to be driven to research. Although the northern lights have historically been a discussion due to the magnitude of the display, modern science recognizes the relationship between the solar storms and satellites and energy on the earth. According to Heavisides (2015) solar storms are closely related to the aurora. It is further noted that the solar storms are so powerful that they could potentially disrupt satellites and destroy electrical transformers on earth. Given the dependency of the modern society on technology and energy sources, such a solar storm could potentially be catastrophic to humanity. Therefore, the modern research that focuses on the northern lights is directed towards the relationship between solar winds, the magnetic fields, and solar storms. Heavisides (2015) adds that it remains difficult to send sensors into the upper atmosphere but that the development of predictive and communicative sensors has laid the foundation for such research. If the astronomers can determine the relationship and predict solar storms of this magnitude, the discoveries may effectively save the planet from devastation.
Understanding the Magnetosphere
Although the potential for devastation drives the continued research, it is also important to note that the atmosphere is protected by a magnetic field similar to that viewable around a comet with the tail of the field pointing away from the sun. According to Brekke and Egeland (1994) the aurora represents particles from the sun as they interfere with the field. When a solar storm occurs, the particles that have penetrated the tail are shaken up and therefore create a collision with the oxygen and nitrogen in the earth’s atmosphere. This occurs at high altitudes which results in the blanket of color known as the northern lights. Under general conditions, the earth’s magnetic field, like that of other planets, is carefully designed to absorb particles into the magnetic field and shield the earth’s atmosphere from any direct negative effects of this phenomenon. However, as the atmosphere continues to change, the potential for harm cannot be dismissed making continuous research essential.
Discussion
Based on the ongoing research about the Northern Lights, it is now possible to explain the current knowledge about this natural wonder. This includes the what, where, and why inquiries that so frequently manifest as further investigation. While there is always a potential for learning new information or gaining a clearer understanding of the Northern Lights, this section will explain what is known at this time.
The first question about the Northern lights is what these displays actually are. According to NASA (n.d.) the Northern Lights provide the realization that our planet is electrically linked to the Sun. The aurora lights present themselves as arcs of light that are narrow in structure and extend from east to west. NASA (n.d.) further explains that the Northern Lights are occasionally viewed as curtains of lights and that the auroras can vary drastically even within a single night. As the night progresses, NASA (n.d.) state that the lights become more active creating a spectacular display.
This leads to the question as to where one can view these natural lightshows. According to NASA (n.d.) the Northern Lights occur in the oval shaped ovals that are approximately 4,000 km (2,500 miles) and encircle the magnetic poles. In the northern hemisphere, this area touches Alaska and Canada, Greenland, northern Scandinavia, Russia, Alaska and Canada. The southern aurora oval is primarily located over the Antarctica but also reaches areas in Australia, Chile, and New Zealand. Author Truls Lynne Hansen (n.d.) adds that this wide range of the lights along with the occurrences of the lights on either magnetic pole mean that they can be viewed from many vantage points, but these chances decrease with the distance towards the equator. NASA (n.d.) clarifies by stating that the lights can be viewed at night time and that the distance may also affect the frequency of being able to view them. In other words, although they occur nightly, the chances of seeing them vary greatly with distance.
. Throughout the paper, several different opinions have been explored as to why these lights occur. Despite the early explanations being widely accepted during those periods, modern investigations are better served with technology and travel. Therefore, the modern understanding of the auroras is far more comprehensive. According to NASA (n.d.) the lights that are viewed are the result of the gases becoming excited and then releasing energy in light form or photons. The space agency then explains that the excitement occurs when the electrons from the magnetosphere collide with the nitrogen and oxygen molecules.
Hansen (n.d.) adds the electrons collide with the highest air particles which means that they occur in excess of 90km above sea level with many occurring at a much higher distance. Based on the distance and the presence of the gases, the lights can vary greatly. The weather conditions on the sun determine the determines the charge of the electrons and, ultimately, whether or not the display will be visible on earth. Hansen (n.d.) explains that the typical green and yellow lights occur when oxygen is most prevalent. Oxygen along with nitrogen can produce a red or orange color. Nitrogen rich air particles produce primarily violet and blue. In brief, as the particles from the sun streamline the connection between the earth and the sun, the earth’s magnetic field grabs hold. Moving towards the night sky and the polar regions, the results of this connection are presented based on the distance, air molecules, and energy of the collision so many miles above the earth. According to NASA (n.d.) this reminds those on earth of the power of the sun and the wonder of the universe.
Conclusion
The northern lights are among the world’s most beautiful phenomenon and have created the foundation for curiosity as to the strength of the universe. However, it is important to remember that the phenomenon is based in science and that research into such phenomenon is essential for advancements that will continue to support the survival of the earth. Although the magnetic field surrounding the earth is designed to protect the atmosphere by absorbing the sun’s particles in the tail of the field, solar storms disrupt these particles and the results are visible at the ground level. Understanding the force behind these solar storms and predicting their occurrence can help to prepare for any potential interference with satellites and energy transformers.
In closing, it has been the intention of this paper to present the science behind the northern lights as evolved since the earliest documented observations. Early observations reveled in the awe of the power of the earth and attributed the phenomenon to the gods of mythology. Later, it was recognized that the phenomenon was based in science and the earth was accredited with the visual display. As the scientific community gained an understanding of chemistry, the investigation into the types of gas compounds responsible for the lights was established. During the same period, Birkeland currents were discovered although they were not proven until after the researcher’s death. Current trends in research focus on the presence of these phenomenon on other planets and how the solar storms affect the magnetic field surrounding the earth’s atmosphere. The northern lights have been the foundation of science and a window into the solar system that supports the planet. Without such a display, many of the discoveries relating to the magnetic field, plasma, and electrons may not have been initiated. Ongoing research as to what efforts could be put into place should the sensors predict a significant solar storm should be conducted to move the science into the future.
