The celestial dance of light is actually a collision of solar particles and our atmosphere
Beyond the shimmering curtains and radiant spirals lies a high-stakes physical collision. When charged particles from the sun strike Earth's upper atmosphere, they excite oxygen and nitrogen atoms, releasing bursts of color. This cosmic interaction creates the breathtaking displays we call the aurora borealis and aurora australis.
The aurora is a product of disturbances in Earth's magnetosphere, driven by the solar wind's speed from coronal holes and mass ejections. As electrons and protons precipitate into the thermosphere and exosphere, they collide with atmospheric constituents. These collisions trigger ionization and excitation, emitting light of varying complexity. The specific colors we see depend on the altitude and the specific atoms involved: at high altitudes, excited oxygen produces red light (630 nm), while at lower altitudes, more frequent collisions favor green (5 57.7 nm) and even blue or purple emissions from nitrogen.
The phenomenon is not uniform across the globe. Most commonly observed in the 'auroral zone'—a band roughly 660 km wide centered near 67° latitude—the display can expand during geomagnetic storms. While the northern lights (aurora borealis) are visible in regions like Alaska, Canada, and Scandinavia, the southern lights (aurora australis) appear in Antarctica, New Zealand, and parts of Australia. In extreme cases, such as the historic Carrington Event, auroras have even been seen in the tropics.
Modern science has uncovered even more nuanced structures. Beyond the classic 'curtains' and 'rays,' researchers have identified 'STEVE,' a ribbon of hot, fast-moving plasma, and 'dune auroras,' which feature parallel stripes resembling sand dunes. While we understand the fundamental mechanism of solar wind interacting with the magnetosphere, the full complexity of all auroral forms remains a subject of ongoing study.
Source: Aurora
