So I got to thinking about lines of latitude recently. Since the Earth is a sphere, that means that, at the equator, a person would have to walk pretty far to go all the way around the Earth. Now, as you head towards the North Pole, if you keep walking along the lines of latitude, you will find that your distance traveled to circumnavigate the Earth becomes shorter and shorter as you approach the pole until finally there are no more lines of latitude to travel, just a point (the North Pole). The teaser is this. Say you're a mile from the North pole, and you look straight down a latitude line that is really close to the North Pole (I dunno, call it 89.999999 degrees N), will you be able to see the back of your own head on the horizon? Why or why not?