This video shows how long it takes for light to travel from Earth to Mars and back again

At this scale, light moves at a snail's pace.

From the YouTube description: "This is the distance between Earth, the Moon and Mars with the correct distances but with Earth, Moon and Mars 20 times bigger (so you can see them!)."

from Boing Boing http://bit.ly/2FJlqyS
via IFTTT