The Northern Lights are known as one of the greatest natural wonders of not only the Arctic, but the world in general. Every year, thousands of tourists flock to the Arctic Circle to witness the night sky light up in a panoply of vivid colors, one of the most unique events that a person can witness. Many Northern Lights viewers may be curious as to what the Northern Lights are made of and what causes them in the first place.
The Northern Lights are generated due to interactions between the Earth’s magnetic field and the sun and manifest as bright, glowing lights in the atmosphere. Read on to learn what the Northern Lights are made of and why they occur.
What Are the Northern Lights Made Of?
As noted above, the Northern Lights, also known as aurora borealis, is created due to interactions between the sun and the Earth’s magnetosphere. While the sun is best known for giving off light, making it possible for life to exist on Earth, light is far from the only thing that the sun admits. All stars, including the sun, give off a variety of particles which are collectively known as “solar wind” due to the way that they reverberate out into space.
Solar wind contains radioactivity and other harmful particles that are deadly to humans and other life. If solar wind were allowed to hit the Earth directly, it would kill humans and all life on the planet’s surface. However, solar wind cannot penetrate the Earth’s atmosphere due to the planet’s magnetic field. The magnetosphere, the protective barrier generated by the Earth’s magnetic field, extends outward into space and deflects or neutralizes solar wind before it can reach the Earth’s surface.
When solar wind impacts the magnetosphere, it collides with particles that are already in the area. In areas where the magnetosphere intersects with the atmosphere (the North and South Poles), these particles include nitrogen, oxygen, and other gases. Solar wind contains charged particles, molecules that contain an electric charge. When these charged particles collide with existing atmospheric particles, the result is a chemical reaction visible as the Northern Lights.
To visualize this process, imagine an atom. Atoms are comprised of a nucleus, a structure consisting of protons (which carry a positive charge) and neutrons (which carry no charge). Virtually all atoms have a set of electrons, which are smaller, negatively charged particles that orbit the nucleus. Ordinarily, atoms are balanced by having an identical number of protons and electrons. The number of neutrons, protons, and electrons determines what substance they form.
When charged particles impact other molecules, this causes “excitement,” a chemical process whereby electrons migrate to higher-energy orbits in the atom, further away from the nucleus. After the atom is no longer excited, the electrons migrate back to their original orbits, in the process giving off photons, which are particles of light. While this process cannot be observed with individual atoms, when a large number of atoms are collectively excited, this gives off a large amount of light. When excitement occurs as a result of solar wind impacting the atmosphere, the resulting process is visible as the Northern Lights.
Excitement is a chemical process seen in other elements of the natural world and is also used by modern technology, most notably in neon lights. Neon signs work by using electricity to excite neon atoms within a tube, resulting in light. The Northern Lights functions in much the same fashion, albeit on a far larger scale and happening naturally.
The color of the Northern Lights is also determined by which types of atmospheric particles are excited by solar wind. Earth’s atmosphere is comprised of 78 percent nitrogen and 21 percent oxygen, with other trace gases making up the remainder, but the composition of the atmosphere is not uniform, with different gases manifesting at different altitudes due to differences in weight and composition. As a result, the colors of the Northern Lights differ depending on how far solar wind can penetrate into the atmosphere.
The most common colors seen in auroras are red, blue, and green. Red and blue auroras are created by nitrogen, while green auroras are created by oxygen. Red auroras occur when solar wind strikes the outermost reaches of the atmosphere, though due to the relative thinness of the atmosphere at this height, red auroras are generally only seen during periods of exceptionally high solar activity. Green and blue auroras occur at lower altitudes, with blue auroras occurring closer to the Earth’s surface due to lack of oxygen in this particular atmospheric band. Ultraviolet and infrared auroras have also been observed with specialized equipment, created by solar interaction with other gases.
The Northern Lights are a unique phenomenon created by Earth’s interactions with the sun. Thanks to the planet’s magnetic field, Earth is protected from harmful solar radiation, and for those lucky enough to visit the Arctic Circle, this process can be observed in the form of auroras, which are safe to look at and some of the most beautiful sights that can be seen in the world. If you’re curious about witnessing the Northern Lights, book a tour so you can see them for yourself.