| MadSci Network: Astronomy |
Holm,
Light does take about 8 minutes to reach us from the Sun, and so we see the Sun as it looked 8 minutes ago. How this affects sunrise and sunset is actually fairly tricky to think about.
We see a sunset when the horizon blocks the light that is coming straight from the Sun into our eyes. The light that we see from the Sun at the time of sunset was emitted from the Sun 8 minutes earlier, when the Sun was actually above the horizon. The light that the Sun emits at the time of sunset, on the other hand, won't reach Earth for another 8 minutes, after the Sun is below the horizon. So, the answer to part of your question is, yes, the light that is emitted from the Sun at the time when we see it set won't reach us until after sunset.
The same process works for sunrise, however. The light that we see from the Sun when it first appears above our horizon was actually emitted 8 minutes earlier, before the Sun was actually above the horizon. This cancels out the effect from sunset, and so the night is not any longer because light takes 8 minutes to reach us from the Sun.