Nitrogen Emissions
Definition
The pinks, purples, and blues that nitrogen adds to auroras, mostly along fast, energetic lower edges.
In plain language
When strong substorms drive electrons unusually deep, they strike nitrogen below the green layer, producing the vivid pink fringes racing along curtain bottoms — a reliable sign the display is peaking.
The science
Molecular nitrogen produces band emission: N₂ first positive (red) and N₂⁺ first negative (blue/violet, 427.8 nm) systems. Mixed red+blue bands appear pink/magenta; sunlit N₂⁺ scattering yields twilight purples.
Why it matters for aurora viewing
Pink edges = energetic electrons = stay outside. Nitrogen colors are the display's intensity gauge written directly into the sky.
See this in action on tonight's data.