Everything you should know about auroras
Discover why auroras form, where they shine, under what conditions they appear, and if they could one day grace your skies.
Auroras are stunning natural light displays that illuminate the sky with vibrant colors. Their beauty is so surreal, they can seem almost unreal, like something out of a dream or a photoshopped image. But they are very much real.
Why do auroras happen?
Auroras are the result of a
natural interaction between the Sun and Earth’s atmosphere.
The Sun continuously emits a stream of charged particles (mostly electrons and protons) known as the solar wind, which travels through space and eventually reaches Earth, interacting with the Earth’s magnetic field. The magnetic field acts like a protective shield, but instead of stopping the particles completely, it channels them toward the poles.
At the magnetic poles, the Earth's magnetic field lines are concentrated and converge, meaning the particles are funneled into the atmosphere. When these charged particles collide with the gases in the Earth’s atmosphere, primarily oxygen and nitrogen, they transfer their energy to these gases, exciting their atoms. This energy causes them to glow, which is what we see as the aurora.
How do auroras get their colors?
The colors of the aurora vary depending on
which gases are excited. Oxygen produces green and red hues, while nitrogen can create purples and blues. The altitude at which these interactions occur also affects the colors, as higher altitudes tend to produce red auroras, while lower altitudes typically result in green.
For most people, auroras remain an unseen wonder. While some witness them regularly, the vast majority never will. This is because auroras don’t appear everywhere—they grace only certain parts of the Earth, leaving most regions untouched.
Why do they shine in some places but not others?
Auroras are typically visible in polar regions because the magnetic field lines are concentrated and direct the charged particles toward the atmosphere. At the equator, the magnetic field lines are more spread out and parallel to the Earth's surface, meaning the solar wind particles are not funneled directly into the atmosphere. Instead, they move along the horizontal field lines, and there isn’t a clear path for them to interact with the atmosphere and produce auroras.
Auroras are best viewed within the auroral zones, two doughnut-shaped belts that encircle the Arctic and Antarctic regions, known as the auroral ovals. In the Northern Hemisphere, this zone includes places like Iceland, Norway, Sweden, Finland, northern Russia (Siberia), Alaska (USA), Canada, Greenland, and parts of southern South America, including Chile and Argentina. These regions experience the aurora borealis, or northern lights.
In the Southern Hemisphere, the auroral zone includes Antarctica, southern Australia, New Zealand, southern South America and parts of the southern oceans, where the phenomenon is called the aurora australis, or southern lights.
Although auroras in the southern hemisphere occur with similar frequency to those in the north, they are less commonly seen due to the lack of land and population at higher latitudes. In the northern hemisphere, regions such as Canada, Greenland, northern Europe, and northern Asia lie north of 45 degrees latitude, offering expansive areas of land and large populations to witness auroras. In contrast, the southern hemisphere has far less land above 45 degrees south latitude. Apart from Antarctica, the only landmasses that may witness auroras are the southern ends of New Zealand, Australia, Chile, Argentina, and a few islands. While auroras are present in the southern hemisphere, the region’s lower population density means fewer people are around to see them.
Where, when and under what conditions can we see them?
Auroras are constantly occurring, but they are only visible under the right conditions. They require darkness to be seen clearly, as their light is faint compared to daylight or artificial lighting. Light pollution from cities can also hinder visibility, so the best chances of seeing auroras are in remote, dark areas. Additionally, solar activity, such as solar storms or coronal mass ejections (CMEs), increases the solar wind, making aurora displays more likely.
Could auroras one day appear where you live?
While auroras are typically confined to the auroral zones, there have been rare occasions when their visibility extends far beyond these regions. One notable event was the 1859 Carrington Event, the most intense geomagnetic storm ever recorded in history. This massive solar storm was so powerful that auroras were observed as far south as the Caribbean, Hawaii, and even parts of South America. In some areas, the auroras were so bright that people could read newspapers by their light in the middle of the night.
This event, caused by a massive coronal mass ejection (CME) from the Sun, created auroras visible even in places where they are normally never seen. So, could people outside the auroral zones ever witness auroras in their own countries? While it’s highly unlikely under normal circumstances, during periods of extreme solar activity—similar to the Carrington Event—there is a possibility that auroras could be seen at lower latitudes. Solar storms or CMEs that are large enough to cause such an event are rare, but they remind us that auroras have the potential to surprise us, even in places far from the poles.