Now is the best time to see colorful lights dance in the sky.
This display of the aurora borealis occurred November 4, 2021, above Condie Regina, Saskatchewan, Canada.
Credit: Dre Erwin Photography/WikiMedia Commons
The breathtaking celestial displays known as the aurorae — the aurora borealis in the Northern Hemisphere and the aurora australis in the Southern Hemisphere — are truly magnificent natural phenomena. These vibrant light shows are not just beautiful, but also a direct consequence of the interaction between our Sun and Earth’s magnetic field.
At its core, an aurora is an electrical phenomenon. It begins with the Sun constantly emitting a stream of charged particles, primarily electrons and protons, into space. This flow is known as the solar wind. During periods of increased solar activity, such as solar flares or coronal mblock ejections (CMEs), the Sun can unleash even more powerful bursts of these particles.
When these energetic solar particles reach Earth, they encounter our planet’s protective magnetic field. Instead of hitting the atmosphere directly, most of these particles are deflected. However, some are funneled along the magnetic field lines towards Earth’s magnetic poles. As they descend into the upper atmosphere, typically at altitudes of 50 to 300 miles (80 to 500 kilometers), these charged particles collide with atoms and molecules of gases present in our atmosphere, primarily nitrogen and oxygen.
These collisions excite the gases, causing them to emit light. The color of the aurora depends on the type of gas being hit and the altitude at which the collision occurs. Oxygen atoms, for instance, typically produce the most common green-yellow glow, often seen at lower altitudes, and can also generate rare red auroras at higher altitudes. Nitrogen molecules contribute to blue and purple hues, which are often observed at the lower edges of auroral displays.
The dynamic shapes and movements of the aurorae — arcs, rays, curtains, and coronas — are due to the constantly changing nature of the solar wind and Earth’s magnetic field. While spectacular and seemingly fragile, these lights are a powerful reminder of the invisible forces at play in our solar system, offering a grand, natural light show that continues to inspire awe.
In mythology, the Norse said the aurora borealis was the Bifrost, the shimmering bridge connecting Midgard (Earth) to Asgard (the realm of the gods), guarded by the god Heimdall. The aurorae were said to be the reflection of the Bifrost’s colors from the Valkyries’ armor as they rode across the sky in their quest to guide fallen warriors to Valhalla. Each flash and swirl showed the movements of these mighty warriors.
If you’ve never seen an aurora, you’re missing out on one of nature’s most amazing displays. And now, with the Sun at its most active during the current solar cycle, the aurora borealis and aurora australis are appearing a lot. I hope the Sun stays active and that you experience this wonderful phenomenon soon.
