Persistent train
A faint glowing trail left behind by some bright meteors that stays visible for seconds, minutes or occasionally longer.
Most meteors vanish instantly, but some bright ones leave a fading streak behind them. A brief glow is called a wake; when it lasts seconds or more it is called a train, and a persistent train may stay visible for minutes. It often slowly twists and drifts as upper-atmosphere winds carry it, turning straight lines into curls and loops.
The glow does not come from hot dust. Researchers think much of the long-lasting light comes from chemical reactions: the meteor deposits metal atoms and energises the thin air at about 80 to 100 kilometres up, and reactions involving oxygen, ozone and metals such as sodium and iron give off light as they proceed. Studying trains helps scientists learn about the chemistry and winds of that hard-to-reach layer of the atmosphere.
Persistent trains are most common from fast, bright meteors, so the Leonids and Perseids often produce them. The 2013 Chelyabinsk superbolide left a huge dust trail that stayed visible in daylight, though that was a smoke trail rather than a glowing train. If you see a train, keep watching it with binoculars, note how long it lasts and its drift, and photograph it if possible.
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