If it only takes 8 minutes for that light to reach the Earth, what took up most of the time? If it only takes 8 minutes for that light to reach the Earth, what took up most of all that time to get to the Earth?
TL;DR: Because light doesn't travel at an infinite speed.
Light travels at exactly 299,792,458 meters per second, and one AU is equal to 149,597,870,700 meters. Therefore, it takes about 500 seconds, or 8 minutes and 20 seconds, for light to travel from the Sun to Earth.