Questions of Latitude: Can You See the Back of Your Head?

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The discussion revolves around the concept of lines of latitude and their relationship to the Earth's spherical shape. As one moves from the equator toward the North Pole, the distance required to circumnavigate the Earth along a line of latitude decreases significantly until it converges at the North Pole. A thought experiment is presented: if a person stands one mile from the North Pole, looking down a latitude line very close to the pole, they would not be able to see the back of their own head on the horizon. This is attributed to the fact that the line of sight does not curve along the latitude line. The conversation also touches on the bending of light around black holes, referencing an article from Scientific American, but this point is less central to the main discussion about latitude and visibility near the poles.
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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?
 
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Ulnarian said:
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?

I do recall an article in Scientific American in the mid-90's maybe that was suggesting that there are such points in proximity to black holes. The light supposedly would bend around the black hole, effectively remaining in orbit. Of course, I think there's a lot of issues involved there, but it was an interesting idea nonetheless...

DaveE
 
Ulnarian said:
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?
Obviously not. You line of sight does not curve with the circular line defining the latitude.

Can you ask a serious question?
 
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