The story of the aurora begins with the Sun. Our star constantly emits a stream of charged particles known as the solar wind. This stream travels across the solar system, carrying with it pieces of the Sun’s magnetic field. When these charged particles reach the Earth, they encounter the planet’s magnetic field, which guides them towards the magnetic poles.
The colors of the aurora are determined by which molecules are involved and how high in the atmosphere the collisions occur. The most common color, a bright green, is produced by oxygen molecules about 60 miles above the Earth. At higher altitudes, above 200 miles, oxygen can produce a rare red aurora. Nitrogen molecules, on the other hand, can produce blue or purplish-red aurora. The variation in colors creates a mesmerizing display, with different hues blending and dancing across the sky.
The aurora typically occurs in an oval-shaped zone around the magnetic poles. The Northern Lights are best seen from countries at high latitudes in the Northern Hemisphere such as Norway, Sweden, Iceland, Canada, and Alaska in the United States. The Southern Lights grace the skies of Antarctica, Tasmania, and the southern tips of New Zealand and Chile. The aurora can occasionally be seen at lower latitudes during periods of strong solar activity, surprising observers far from the poles with a rare glimpse of its beauty.
The aurora has been a source of wonder and inspiration throughout human history, featuring in the mythology and folklore of many cultures. The Vikings may have seen the lights as reflections of the shields of the Valkyries, while some Indigenous peoples considered them the spirits of their ancestors. These interpretations, as diverse as they are, speak to the profound impact of the aurora on the human imagination
While the aurora provides a stunning natural spectacle, it also offers scientists valuable insights into the Earth’s magnetic field, the solar wind, and the complex interactions that occur in the space environment. Understanding the aurora helps researchers predict space weather events, which can impact satellite communications, navigation systems, and even power grids on Earth.