After my first comment was a joke, let me give you a serious answer: twilight is not the time from sunrise to sunset but the time around sunrise and around sunset. When the sun rises at 6am and sets at 6pm, twilight doesn't last 12h. Noon is never twilight. Twilight is the time between day and night, not the daytime.

I might be wrong though since the only true thing about my last comment was that I'm not a native speaker, we have a cognate that means what I've described and I'm pretty sure, the English word means the same.