Picture yourself outside on a clear dark night. Low on the horizon you notice a faint glow of greenish light which forms an arch, stretching lazily across the sky. As time passes, additional bands of light form and drift overhead, slowly brightening to form giant curtains in the sky that slowly wave as if a gentle breeze were blowing. Suddenly, the bottom of the curtains brighten with a reddish tint and ripple faster. Blues and purples appear. As the curtains pass directly overhead, you see bright points of light that swirl like a pinwheel. The entire sky seems to be full of color and motion. Then, after several minutes, everything fades into a warm green glow.
The short answer to how the aurora happens is that energetic electrically charged particles (mostly electrons) accelerate along the magnetic field lines into the upper atmosphere, where they collide with gas atoms, causing the atoms to give off light.
Auroras can be spotted throughout the world and on other planets. It is most visible closer to the poles due to the longer periods of darkness and the magnetic field.
Auroras are associated with the solar wind, a flow of ions continuously flowing outward from the sun. The Earth’s magnetic field traps these particles, many of which travel toward the poles where they are accelerated toward earth. Collisions between these ions and atmospheric atoms and molecules causes energy releases in the form of auroras appearing in large circles around the poles. Auroras are more frequent and brighter during the intense phase of the solar cycle when coronal mass ejections increase the intensity of the solar wind.Seen from space, these fiery curtains form a thin ring in the shape of a monk’s tonsure.
