APOD: Polar Ring Galaxy NGC 2685 (2014 Mar 14)

[Nitpicker]

This isn't even a matter of words used in APOD descriptions anymore. This is a matter of a simple geometric object not having a name. "Lens" is more generalized and I had not thought of it quite that way before. What when the lens shape is very fat when the two intersecting circles approach overlapping?

Gosh I'm slow ... it just dawned on me that this is where the word lenticular comes from: a volume of revolution of a lens, or simply descriptive of a lens. (You're also right that vesica piscis is too specific for the shape we were trying to name.)

[geckzilla]

A lenticular cloud is revolved about its major axis. A lenticular ball is revolved about its semi-major axis. Toss me that lenticular ball.

[Nitpicker]

When we were kids, we used to play a kind of football called Kill the Dill with the Pill. Good times.

[owlice]

I would feel very sorry indeed if APOD stopped using "football shaped" to describe something that is, indeed, shaped like a football. Oval != football shaped.
Cigar != Oval, and it certainly != football shaped.

The objection to use of the term is no more than "I don't like this" (which we see with so many different thises), and the standard reply to "I don't like this [image/text/planet/view/explanation/vocabulary]" is "well, then, wait a day, and you'll have an all new APOD to see."

[Nitpicker]

I would feel very sorry indeed if APOD stopped using "football shaped" to describe something that is, indeed, shaped like a football. Oval != football shaped.
Cigar != Oval, and it certainly != football shaped.

The objection to use of the term is no more than "I don't like this" (which we see with so many different thises), and the standard reply to "I don't like this [image/text/planet/view/explanation/vocabulary]" is "well, then, wait a day, and you'll have an all new APOD to see."

Owlice, if you are telling me that an American football is not shaped like an oval, then I can only imagine you have idealized the shape of an American football into a lens shape. But I think I have shown quite clearly, that one can simply and conventionally define an oval to give a better approximation of an American football, than a lens. A lens is the best name to describe a lens, but a pointed oval is perhaps more easily understood and accepted by a wide, global readership.

I would probably never have described this galaxy, nor any football, as lens shaped, and not just because I've only just re-discovered the word as a shape. But I might have said an oval, or a pointy oval in common language. Each time I look at the image of the galaxy, I can't decide if the ends appear pointy or rounded.

[Ann]

Nitpicker wrote:
Each time I look at the image of the galaxy, I can't decide if the ends appear pointy or rounded.

To the best of my completely amateur understanding, galaxies never have pointy ends.

Admittedly though, NGC 2683 looks remarkably pointy-edged! Then again, it is the "spiral arms" that look pointy, not the main elliptical body of the galaxy. And the spiral arms of NGC 2685 are rather anomalous.

Ann

[Nitpicker]

Looking back, the first use of the words football and shape together in this topic, was not in the explanation, but in a reply:

it is shaped more like a football

I don't think there is too much wrong with that, unless you can't get past the fact that some footballs aren't spherical. One cannot describe any nebulous object with so much precision.

But both geckzilla and owlice have really surprised me by saying that "football shaped" is not the same as oval. Is this the general consensus in the USA? If it is, and if you think that the fine distinction between lens and oval shapes is critical, then I definitely think that "football shaped" is a particularly poor term, regardless of whether your readership is in the USA, or global.

[owlice]

Nitpicker, I am saying that I would never use the word "oval" to describe something that is football shaped, nor would I use the word "cigar" to describe something that is football shaped. These words are not adequate.

If something is shaped like a football, it's shaped like an football, and that is the word I would use to describe its shape, and as an American, yes, I'd mean American football. Of course, you're free to use puggle casing, prolate spherical, almond-shaped, pointed oval, lenticular, or fish bladderish to describe the shape if you'd like. The APOD editors have used "football shaped" in APOD text (and yes, I did know they didn't this time), and I think that's perfectly okay, and in fact, preferable to any of the alternatives you've mentioned.

[Nitpicker]

Well, now, this is getting a bit interesting (even if only to me). I honestly had no idea that "football shaped" was used by Americans (or anyone else) to mean the exact shape of an American football, to the exclusion of all other non-spherical footballs. That is a very specific shape, that would not apply to many objects, apart from American footballs. And I have previously lived in America for several years. I have always held the term "football shaped" to be informal and imprecise. Whereas I hold "oval" to be a common term, not as informal, but just as imprecise. I also own an American football, a Rugby Union ball, an Australian football and a Soccer ball. Apart from the Soccer ball, they are all similar in shape (I am beginning to wonder if you are aware of this). I have said it already and have even demonstrated it graphically for the American football: all non-spherical footballs are ovals. The Rugby ball is closest to an ellipse (a specific kind of oval) and the American football is closest to a lens (but not quite, it is still an oval).

How would you describe the shape of an American football, without saying "football shaped"? Would you say lens, pointy oval, oval, or something else?

Why is oval inadequate here? Is it merely because an American football is only a certain kind of oval? Or is it because you idealize an American football into a particular kind of lens? I am legitimately curious.

(I would never use the term "cigar shaped" for any football, and haven't here. I would use it for a particularly narrow oval or lens, or even a cylinder with rounded or pointed ends. I believe these to be the common applications of the term.)

Edit: I understand that you prefer "football shaped" and will continue to use it, regardless. That is fine. I really don't mind. But now I just want to know what you mean by it, exactly.

[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.

[owlice]

geckzilla, that is a wonderful analogy!

Nitpicker, see geckzilla's post above! I guess if I ran across someone who had no idea what this shape was, I might use prolate spheroid. Biconvex lens doesn't quite cut it, as viewed from above the convex surface, a lens is often a circle. More likely, I would simply draw the shape or show an image of a football. It would never occur to me to use oval to describe the shape of a football.

An aside: when my son was just beginning to learn to talk, lima beans were ovs for "oval" (he was learning shapes, too, at that time). He loved these, and would get very excited when ovs were among the mixed frozen veggies on his tray. "Ovs! Ovs!" I've never seen anyone so excited about lima beans! (I am not a fan of them.)

[neufer]

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.

Click to play embedded YouTube video.

• The Fatigues

Jerry: So you saw Banya's act?

Abby: He got two minutes into that Ovaltine thing and I just couldn't take it anymore. Why is he so obsessed with Ovaltine?

Jerry: He just thinks that anything that dissolves in milk is funny.

Kenny Banya (reading): Why do they call it Ovaltine? The mug is round. The jar is round. They should call it round tine. That's gold, Jerry! Gold!

[Nitpicker]

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.

[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.

But your particular shade of blue-green is so specific as to be barely useful to describe anything but itself.

A shape can be extremely specific, can it not? A circle can be defined in as little as three parameters and is only ever one specific shape. To satisfy your desire for variety, however, I have attached several examples of what shape I consider the football to fall into the category of.

[Nitpicker]

Thank you geckzilla. That certainly does help to clarify what you mean by "football shaped", that is, symmetric and asymmetric lenses. But I really doubt that is what most people (even most Americans) mean when they use the term. Does anyone else have an opinion?

I understand "football shaped" to mean anything more or less like these shapes, but not necessarily so symmetric:

Not quite to scale, but accurate for shape.

These can all be sufficiently described as ovals.

[Chris Peterson]

Thank you geckzilla. That certainly does help to clarify what you mean by "football shaped, that is, symmetric and asymmetric lenses. But I really doubt that is what most people (even most Americans) mean when they use the term. Does anyone else have an opinion?

Context is everything. If the discussion were about footballs, the first of Geck's examples is the only one I'd consider valid. If the discussion were about galaxies, I'd consider one looking like any of the examples to be "football shaped". Seriously, as we all strain to see horses and witches in astronomical objects, nobody should have any problem with "football shaped" to describe anything that is even vaguely oval, ovoid, lenticular, or any number of other equally reasonable and substantially equivalent terms.

[geckzilla]

You see that one of those looks like a gibbous moon. I wouldn't call a gibbous moon an oval. Anyway, I'm not saying that anyone should call anything other than what they want. I'm saying it is in this shape category and not an oval. Do you call lenses or gibbous moons ovals? You could very coarsely define both of those as a ovals. The English language just isn't quite succeeding in this area. Kind of like how you don't have a word for the front of your elbow. You just call it the front of your elbow, unless you happen to be a doctor, in which case you might call it antecubital. Anyway, it's not my fault the English language has no word other than lens for this shape and that lens does not seem a proper word in many cases. It's a shame because it can be applied to quite a few things. Leaves, scales, petals, eyes, various nuts and seeds, spindles, many animals' pupils, etc...

[Nitpicker]

Thank you geckzilla. That certainly does help to clarify what you mean by "football shaped, that is, symmetric and asymmetric lenses. But I really doubt that is what most people (even most Americans) mean when they use the term. Does anyone else have an opinion?

Context is everything. If the discussion were about footballs, the first of Geck's examples is the only one I'd consider valid. If the discussion were about galaxies, I'd consider one looking like any of the examples to be "football shaped". Seriously, as we all strain to see horses and witches in astronomical objects, nobody should have any problem with "football shaped" to describe anything that is even vaguely oval, ovoid, lenticular, or any number of other equally reasonable and substantially equivalent terms.

Thank you Chris. I'll note that the discussion of the shape here, has never been to describe an actual football. If we start defining the shape of a football as "football shaped" then I really think we should stay in bed and forget about it.

The difference we are arguing about here is only the degree of pointedness of the ends. Pffft (sound of deflating football of any shape).

(And geckzilla, yes, I think some of my photos of the gibbous Moon do make it look rather oval. It is only the idealized version -- an assymetric lens -- which has sharp points. Same goes for the American football.)

[Nitpicker]

Do you call lenses or gibbous moons ovals? You could very coarsely define both of those as a ovals. The English language just isn't quite succeeding in this area. Kind of like how you don't have a word for the front of your elbow. You just call it the front of your elbow, unless you happen to be a doctor, in which case you might call it antecubital. Anyway, it's not my fault the English language has no word other than lens for this shape and that lens does not seem a proper word in many cases. It's a shame because it can be applied to quite a few things. Leaves, scales, petals, eyes, various nuts and seeds, spindles, many animals' pupils, etc...

You could delete only a tiny number of black pixels at the ends of your black and white lens shapes, such that I would be happy to suddenly start calling them oval. The difference is so minute, and it has a psychological component.

Lentils got their name because of their lens shape. I love lentils. I say we reclaim the word "lens" as a popular shape name, for those nitpicky occasions where we really mean "lens" and not "oval".

[Chris Peterson]

I say we reclaim the word "lens" as a popular shape name, for those nitpicky occasions where we really mean "lens" and not "oval". :ssmile:

The usual adjective is "lenticular", and I'm not sure where we would reclaim it from, as it remains in very wide usage.

[geckzilla]

You could delete only a tiny number of black pixels at the ends of your black and white lens shapes, such that I would be happy to suddenly start calling them oval. The difference is so minute, and it has a psychological component.

Oh, gosh. There are a few other shapes we could get rid of and just call slightly pointy ovals. Octagons are basically just circles with a few extra pixels. Why do we even have those? And yet a pencil shaped like an octagon will not roll. Luckily some brilliant minds managed to make that distinction.

[Nitpicker]

You could delete only a tiny number of black pixels at the ends of your black and white lens shapes, such that I would be happy to suddenly start calling them oval. The difference is so minute, and it has a psychological component.

Oh, gosh. There are a few other shapes we could get rid of and just call slightly pointy ovals. Octagons are basically just circles with a few extra pixels. Why do we even have those? And yet a pencil shaped like an octagon will not roll. Luckily some brilliant minds managed to make that distinction.

I think you are just arguing for the sake of arguing now (and still selectively). I don't want to get rid of shapes. I was trying to say that all one has to do to convert a lens to an oval is to put a small radius on each end. Whether the shape has pointy ends or rounded ends makes very little difference to the overall appearance. In other words, the difference between some lenses and some ovals is arbitrary in practice, and we appear to arbitrate them differently.

Visually, there isn't much difference between a small octagon and a small circle. Mathematically and conceptually, there is a huge difference. Practically, there is just enough difference between a hexagonal pencil (octagonal? stop with the cultural differences already!) and a round one, to prevent the former from rolling off a sloping drawing board (which these days is also pretty conceptual).

[Nitpicker]

I say we reclaim the word "lens" as a popular shape name, for those nitpicky occasions where we really mean "lens" and not "oval".

The usual adjective is "lenticular", and I'm not sure where we would reclaim it from, as it remains in very wide usage.

In my world, it is uncommon to call the shape of the intersection of two circles a lens, or to say it is lenticular. But I'd like to see it become as common as the shape names: square, rectangle, circle, ellipse, oval and crescent (and their adjectives).

[geckzilla]

We have hexagonal and tringular and flat pencils, too. I'm not sure we have octagonal ones. Probably somewhere. Hexagons were too angular to pick on, though. So a lens with precise angles at the end is not mechanically useful to us, so we do not need a special name for it other than the name it already has, which works well in the optics world. You can imagine that if we did live in a world where this particular shape played a role in our every day lives, it would have a particular name. Something like the word football as it is known in the U.S., but known around the world. If you take this shape and round off just the bottom, you'd think you'd be that much closer to an oval. Instead, it turns into a teardrop. Waah.

Yes, I am still arguing because this argument amuses me.

[owlice]

Lentils got their name because of their lens shape. I love lentils. I say we reclaim the word "lens" as a popular shape name, for those nitpicky occasions where we really mean "lens" and not "oval".

Lentils came first; I'm reasonably certain the word "lens" comes from lentil, not the other way around.

I love lentils, too, especially lentil soup and lentil-bulgur salad. Nom nom nom! (Our Himalayan tripod cat's name is Lentil, more a reference to our initial perception of the size of his brain than anything else. He's a lovely very nice cat [except for the considering-people-prey thing].)

Prolate spheroid is not the correct term for an American football, despite what it says all over the internet.

That's why I said I'd probably just draw a football or find a picture of one.

But your particular shade of blue-green is so specific as to be barely useful to describe anything but itself.

According to you, one who is not able to see (or at least appreciate) the distinction. There are sounds in languages I don't speak that are different for a native speaker but the same for me; I cannot tell the difference between them. The sky is green, except it isn't. A football is oval, except it isn't. Does A=440, or does A=415? Or something else? Is it a microtone, or an Eb that is a little... well, flat? Annoying to my ear, perhaps, but for someone in a different culture, a perfectly good tone.