The northern lights (aurora borealis) and their southern counterpart (aurora australis) are among the most spectacular natural phenomena on Earth. These shimmering curtains of light are the visible result of collisions between charged particles from the sun and gases in Earth's atmosphere.
The Solar Connection
The sun continuously emits a stream of charged particles called the solar wind. During solar flares and coronal mass ejections, the sun releases particularly intense bursts of these particles. When they reach Earth (typically 1-3 days after a solar event), they interact with our planet's magnetic field.
Earth's Magnetic Shield
Earth's magnetic field, generated by the churning molten iron in the outer core, extends far into space and deflects most of the solar wind. However, at the magnetic poles, the field lines converge and funnel charged particles down into the upper atmosphere.
The Light Show
As solar particles collide with atmospheric gases at altitudes of 60 to 200 miles, they transfer energy to the gas atoms, exciting their electrons to higher energy states. When the electrons return to their normal state, they release the energy as photons of light. Different gases produce different colors.
The Colors
Green: the most common aurora color, produced by oxygen molecules at altitudes of 60-150 miles. Red: oxygen at higher altitudes (above 150 miles). Purple/blue: nitrogen. Pink: a mix of nitrogen and oxygen at lower altitudes. The specific colors depend on the altitude of the collision and the gas species involved.
Where and When to See Them
Auroras are most visible in an oval-shaped zone around the magnetic poles (roughly 65-72 degrees latitude). Iceland, northern Norway, Sweden, Finland, Canada, and Alaska are prime viewing locations. During intense solar storms, auroras can be visible at much lower latitudes. Best viewing conditions: dark, clear skies away from light pollution, during the winter months when nights are longest.
The Solar Cycle
Aurora activity follows the 11-year solar cycle. Near solar maximum, more frequent and intense solar events produce more spectacular and widespread auroras. The current solar cycle (25) peaked around 2024-2025, making recent years excellent for aurora viewing.
