If you're not reading the article - it's long and not that interesting if you're not into it - then just go and check out the picture. The interesting part is t

If you're not reading the article - it's long and not that interesting if you're not into it - then just go and check out the picture. The interesting part is the lightning strike seemingly skipping a distance. The exhaust is very conductive (the gases are ionized/a plasma due to temperature) and thereby serves as a sort of shortcut between two points in the atmosphere (and the metallic rocket body does that of course as well). The skipped part is where no combustion is taking place anymore but there are still enough ions to conduct. Below that, the lightning strike propagates as usual. It's not clearly visible but the lightning strike will be most likely following the exhaust trail.