The Northern Lights and the Sun
The Northern Lights are a well-known phenomenon that attracts countless tourists to the Arctic every year. A dazzling nighttime display of brilliant colors, the Northern Lights has captivated humans for generations, with numerous cultures spawning their own myths and legends to explain their appearance. Thanks to modern science, we now know that the Northern Lights are the product of Earth’s unique relationship to the sun.
While the sun is best-known for providing light and heat during the day, it also has a number of other effects on the planet, the Northern Lights being one of the most prominent. Read on to learn about the role the sun plays in creating the Northern Lights.
The Northern Lights and the Sun
The Northern Lights are created by solar wind, the scientific term for the streams of particles that the sun gives off on a regular basis. Solar wind is full of radiation and is deadly to life, but the Earth is protected from solar wind by the magnetosphere, an invisible barrier that surrounds the planet and is created by its magnetic field. The magnetosphere deflects or neutralizes solar wind when it approaches Earth, keeping the planet safe from harm.
Most of the magnetosphere is located in outer space, some distance from the planet itself, but because the magnetosphere is created by Earth’s magnetic field, it converges with the atmosphere at the North and South Poles, where the magnetic field originates. Because of this, in the Arctic and Antarctic Circles, solar wind enters the atmosphere before it is neutralized by the magnetosphere, creating the visual effect known as the Northern Lights.
The Northern Lights works by exciting air atoms through the charged particles contained within solar wind. All atoms are composed of a nucleus, containing protons and neutrons, and one or more orbits containing electrons. When an atom becomes excited, its electrons migrate to higher-energy orbits that are further away from the nucleus. When the atom ceases to be excited, its electrons return to their original orbits, giving off light in the process. When this happens to many air atoms all at once, the result is a massive display of light in the form of an aurora.
Because auroras occur as a result of solar wind, greater amounts of wind result in more frequent and stronger auroras. During periods of intense solar activity, auroras will actually appear outside of the polar regions. The last time this occurred was the Carrington Event of 1859, a solar storm that caused auroras across much of the northern hemisphere and also damaged telegraph wires, causing them to explode or give off sparks.
Scientists have identified an 11-year solar cycle, during which the amount of solar wind generated by the sun rises and falls. This cycle is tied to the reversal of the sun’s magnetic poles; when the poles are located near the equator, solar wind emissions become larger and more frequent. During the low point of the cycle, solar wind activity declines to a minimum. Scientists have pinpointed the next peak of solar activity to occur around 2025. Note that during a lull in solar activity, auroras do not stop occurring; they simply occur less often.
In addition to this solar cycle, scientists have identified longer solar cycles that can last for a century or more. 2008 signaled the end of the Modern Maximum, a period of heightened solar activity that began in 1914 and caused higher temperatures on Earth and more frequent auroras. The Medieval Maximum was a similar period of increased solar activity from 1100 to 1250, and its end caused the Little Ice Age, a period in which temperatures cooled around the globe.
Scientists do not yet know the causes of these longer solar cycles or have identified a means by which they can be predicted. However, solar activity has noticeably declined since 2008, suggesting that the sun has entered into a new minimum period. This means that for the future, the Northern Lights will occur less frequently than it did during the Modern Maximum, and auroras that do appear will be smaller as well.
Note that despite some alarmist claims, the Northern Lights will never go away entirely. The sun is always giving off solar wind to some degree, and as long as solar wind continues to impact the magnetosphere, auroras will be visible in the polar regions. However, the reduced solar activity means that auroras will not happen as frequently as they did during the Modern Maximum, and it also means that they will not be as large as auroras during that period.
Conclusion
The Northern Lights is just one example of the Earth’s relationship with the sun. While the sun’s light and heat are responsible for making life on Earth possible, the solar wind that it gives off is dangerous; fortunately, the magnetosphere’s deflective properties keep solar wind from harming the planet. The Northern Lights is intimately linked with the sun’s activity, and as long as the sun continues to exist, auroras will continue to be seen across the polar regions, even if their frequency changes depending on the solar cycle.