Twilight is the time between dawn and sunrise and the time between sunset and dusk. Sunlight scattered in the upper atmosphere illuminates the lower atmosphere, and the surface of the Earth isn't completely lit or completely dark. The sun itself isn't actually visible because it hasn't yet come over the horizon (sunrise) or it has passed below the horizon (sunset). Often confused with dusk, twilight is specifically defined as the period before or after night-time during which it's possible to c… (More on Twilight)