Answer: Happy Earth Day folks! If our sun suddenly shut down, we would not know about it for approximately eight minutes. The sun we look at is actually the sun as it was some eight minutes ago. This is because the light shining from the sun, traveling at about 186,000 miles a second, takes 500 seconds to travel across the millions of miles of space that separate us from the sun. The sunlight will sweep past Mercury in 3.22 minutes, Venus in 6.01 minutes, and reach Earth 8.32 minutes later. Neptune, the most distant planet, takes 4.16 hours for light to reach.