In the far North, majestic colored lights often dance and shimmer in the nighttime sky. No two displays are ever the same. Sometimes it’s a meek green glow low in the north, shyly pulsing as if not wanting to be seen. Other times multiple shades of greens, reds, purples, and even blues explode across the sky as rippling curtains of multi-colored light fill the heavens. These are the northern lights, the aurora borealis. To see them, you must voyage into the Arctic. But the excursion is worth the effort.
A display of the aurora borealis happens when charged particles are blasted out from the Sun and ride the solar wind to Earth, where our planet’s magnetic field captures some and deflects the rest. The trapped particles are drawn in toward Earth’s magnetic poles, where they smash into atoms and molecules in Earth’s upper atmosphere in a region known as the auroral oval. Each collision produces a tiny spark of light; millions of collisions light up the night sky.
The colors of the northern lights vary, depending on which atmospheric atoms are struck, and at what height. The most common aurora color is green, the result of collisions between solar particles and oxygen atoms between 60 and 180 miles up. Higher up, this same collision combination yields red aurora. Lower down, solar particles striking nitrogen molecules produces purple fringes often seen at the base of green curtain auroras.