Definition
A natural light display in the night sky, most often seen at high northern latitudes, caused by charged particles from the sun interacting with gases in the upper atmosphere. The display typically appears as shifting curtains, arcs, or glows of green, red, or purple light along the northern horizon.
Plain English
The northern lights — colored, moving lights in the night sky seen mostly when flying in or near northern regions.
Context Anchor
In night flying, especially in northern areas, an aurora borealis may appear near the horizon and can be part of a false horizon illusion.
Derivation
From Latin 'aurora' meaning 'dawn' (the Roman goddess of the dawn) and 'borealis' meaning 'northern,' from the Greek 'Boreas,' the god of the north wind. Literally 'northern dawn' — a fitting name for a glow that lights up the northern sky.
Why Pilots Care
It can provide unexpected light sources that interfere with night visual references and contribute to spatial disorientation.
Grounding Statement
On a dark night with little ground lighting, a wide aurora can make the sky look as if it has a bright edge or line even when the real horizon cannot be seen.
Intuition Check
Do not treat an aurora borealis as a reliable horizon. It is a light display in the sky, and its shape or angle may not match the real horizon.
Example Sentence 1
Flying north on a clear winter night, the pilot saw the aurora borealis along the horizon and was careful to cross-check the attitude indicator rather than trust the outside view.
Example Sentence 2
The pilot used the steady position of the aurora borealis as a rough reference while establishing a visual horizon.