Is Earth a sphere?

[Bullgrit]

If you thought the difference between the polar and equatorial radius was too small to worry about, the difference between including the atmosphere and not including it is even smaller.

But apparently the very small difference of pole vs. equatorial diameter is enough for someone to say Earth is not a sphere, but the envelope of atmosphere around the planet is too small to count in the measurement.

Again, I'm not arguing one way or another. I'm not saying anything is right or wrong. I'm just noting choices as interesting.

And the context of the original question has been asked for at least a couple of times in this thread. The context is "a simple question posed on a general discussion forum in a thread tagged as 'Science'".

Here's another question: If a non-scientist college professor where to refer to Earth as a sphere, would you think him wrong? Would you point out the error?

And lastly for this post, I note another interesting thing in the responses here: "Earth" vs. "the Earth"
When I'm speaking, I could say either without thinking about it. When I write, (that is, when I'm thinking about it), I drop the article. I couple of times in this thread I've had to backspace and remove the "the".

Bullgrit

 

[Leif]

Here's another question: If a non-scientist college professor where to refer to Earth as a sphere, would you think him wrong? Would you point out the error?
Bullgrit

Depends. Is the non-scientist prof. a professor of the "art" of mathematics? And, of infinitely greater importance, am I presumed to be depending upon this professor for a grade this semester?

 

[Hand of Evil]

gee, I answered no because I went with Planet knowing the gas giant supporters are out to get the smaller planet declassified like Pluto! I don't want to say Bullgrit is filled with gas but...

It was also based on too much science shows and math on what a sphere is.

 

[Umbran]

But apparently the very small difference of pole vs. equatorial diameter is enough for someone to say Earth is not a sphere, but the envelope of atmosphere around the planet is too small to count in the measurement.

Yes. If A > B, one can reasonably choose to worry about A, but not about B. Pretty simple, really. Not even all that interesting.

Here's another question: If a non-scientist college professor where to refer to Earth as a sphere, would you think him wrong? Would you point out the error?

No flat answer for that - who the guy is in his day job is only one part of the social context.

 

[tomBitonti]

How much we can resolve with a slight change:

Is the Earth a sphere. In a technical sense, no. But in a technical sense, "sphere" is a mathematical concept not applicable to real objects. For a real object, "spherical" is more correct to use.

Is an unholed bowling ball (before the finger holes are drilled) a sphere? It is intended to be a sphere, but no matter how perfect, it won't be perfect, and won't be a sphere. However, a bowling ball, and the earth, are undeniably spherical.

Thx!

TomB

 

[Nytmare]

 

[Leif]

You've got to love Neil DeGrasse Tyson, a/k/a Dr. Awesome, but Bill Maher is a total and complete waste of space.

 

[Fast Learner]

I voted "no" due to the oblate spheroid issue. While it's easy to say that the difference doesn't matter, it matters a lot in certain circumstances.

I wrote an app where, as part of it, you could find out where other users were, providing the direction and distance to them. Using standard trigonometry of a sphere proved to be far too inaccurate. Instead I had to use the Haversine formula to calculate the "great circle distance" between points, which works on an oblate spheroid.

So, no, the Earth is not the shape of a true sphere, or even all that close.

 

[Morrus]

The distinction, I suspect, is no whether it matters whether it's a sphere - clearly it does - but whether it matters whether we call it a sphere, and in what conversational contexts.

And given Bullgrit has now defined the context as a not-really-a-context-just-a-medium, the only real answer is "I guess, if you want". Or, in short, the question needs a context to have any meaning, and "on a messageboard" is just a place, not a context.

 

[gamerprinter]

I think the term "sphere" is clear enough, without a need for "perfect" to added in front. It is either a sphere or not. Consider a four sided object, if equal length lines with 90 degree corners, I'd call that a square. If lines or angles are off, I wouldn't call it squarish or almost a square. I'd call it a rectangle, parallelogram, rhombus, trapezoid or a quadrilateral shape - or whatever it happened to be.

Being an artist, I perceive my world visually, and exact definitions when they are available should be used even in simple conversation to describe what we see. I'm not trying to be anal, I just call things as I see them and call them by their proper names, if I know them.