by Nitpicker » Sun Mar 23, 2014 10:45 pm
geckzilla wrote:Oval to me is rounder than a football. A football has some angularity to it which is very unlike an oval. This is pretty much like if you are in a culture which makes no distinction between green and blue and then you come to us and try to tell us that all of these blue things are green. The sky isn't green.
But your particular shade of blue-green is so specific as to be barely useful to describe anything but itself.
It appears "football shaped", to you, is "very unlike" an oval, but a kind of lens, or a kind of lens with slightly rounded ends (which is actually an oval). Sorry, but that is so specific that it has introduced a level of confusion I previously never considered. I am starting to side with the Soccer nuts (but not quite). To me, a lens is so similar to an oval that they are barely worth discriminating between, unless you use technical terms. And "football shaped" could cover both (and more), in a loose, inclusive kind of way. The main point is that "football shaped" means not circular. I am almost certain that mine is the more universal meaning of the term, and this topic has not changed my opinion. But it has really been an eye-opener to me, and has strengthened my resolve to avoid the term "football shaped", as it
is confusing, contentious and too informal for a wide audience.
I even went back through old APODs, looking for the shapes that were described as "football shaped". With the possible exception of this day's APOD, they all looked more oval than anything else.
Prolate spheroid is not the correct term for an American football, despite what it says all over the internet. A prolate spheroid is specifically the 3-D shape you get when you rotate a 2-D ellipse (a circle scaled linearly up or down in one axis) about its major axis. Geckzilla demonstrated graphically that this doesn't fit the American football. But given the right eccentricity, a prolate spheroid is closest to a modern Rugby ball. The American football started out life as a Rugby ball, and progressively became more pointy over time, with a smaller radius at the ends. The Rugby ball has also changed over the years, but not as much. An Australian football is a different ball again, which I emphasize only because I just read an old APOD which implied Rugby and Australian football were the same, when they are not at all. American football and the Rugby codes are more similar to each other, than any of the other codes.
[quote="geckzilla"]Oval to me is rounder than a football. A football has some angularity to it which is very unlike an oval. This is pretty much like if you are in a culture which makes no distinction between green and blue and then you come to us and try to tell us that all of these blue things are green. The sky isn't green.[/quote]
But your particular shade of blue-green is so specific as to be barely useful to describe anything but itself.
It appears "football shaped", to you, is "very unlike" an oval, but a kind of lens, or a kind of lens with slightly rounded ends (which is actually an oval). Sorry, but that is so specific that it has introduced a level of confusion I previously never considered. I am starting to side with the Soccer nuts (but not quite). To me, a lens is so similar to an oval that they are barely worth discriminating between, unless you use technical terms. And "football shaped" could cover both (and more), in a loose, inclusive kind of way. The main point is that "football shaped" means not circular. I am almost certain that mine is the more universal meaning of the term, and this topic has not changed my opinion. But it has really been an eye-opener to me, and has strengthened my resolve to avoid the term "football shaped", as it [u]is[/u] confusing, contentious and too informal for a wide audience.
I even went back through old APODs, looking for the shapes that were described as "football shaped". With the possible exception of this day's APOD, they all looked more oval than anything else.
Prolate spheroid is not the correct term for an American football, despite what it says all over the internet. A prolate spheroid is specifically the 3-D shape you get when you rotate a 2-D ellipse (a circle scaled linearly up or down in one axis) about its major axis. Geckzilla demonstrated graphically that this doesn't fit the American football. But given the right eccentricity, a prolate spheroid is closest to a modern Rugby ball. The American football started out life as a Rugby ball, and progressively became more pointy over time, with a smaller radius at the ends. The Rugby ball has also changed over the years, but not as much. An Australian football is a different ball again, which I emphasize only because I just read an old APOD which implied Rugby and Australian football were the same, when they are not at all. American football and the Rugby codes are more similar to each other, than any of the other codes.