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I know that the best possible approximation of the shape of earth is an oblate sphere. But people also call it as geo-spherical shape of the Earth. What is the meaning of geospherical shape? Does this mean that the shape of Earth itself is unique and hence a word geospherical is used to define that shape but for mathematical calculations we use oblate as the closest approximation.

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    $\begingroup$ Welcome. Do you have a link to where that term is used, and a hint to what you're up to ? It is, in appriximation, on oblate spheroid. Whatever approximation to the earth's shape one uses, it totally depends on the use case. That "oblate spheroid" thing is called an ellipsoid. WGS84 datum is a computer friendly representation and approximation to the earth ellipsoid. $\endgroup$
    – user20217
    May 4 '20 at 10:50
  • $\begingroup$ Thanks. I understand the theory behind earth approxmiating as oblate spheroid. But my que is I heard a renowned speaker saying earths shape is called as geospherical. But I am unable to understand the meaning of this word. Is it correct to say earth's shape is geospherical. PS: I don't have the link right now. $\endgroup$
    – Talha
    May 5 '20 at 19:38
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    $\begingroup$ @Talha I haven't heard the term "geospherical". The description sounds like something that is normally called the "geoid"? $\endgroup$ May 6 '20 at 20:23
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    $\begingroup$ The Geosphere is the solid bits of the earth. vocabulary.com/dictionary/geosphere. Sometimes it's just easier to google things. lmgtfy.com/?q=geosphere+definition $\endgroup$ May 6 '20 at 21:13
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"Does this mean that the shape of Earth itself is unique...?"

Yes, the Earth's shape is what is called a geoid. This is an exaggerated portrayal of it: enter image description here

But the best approximation is an oblate ellipsoid of course.

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  • $\begingroup$ Thanks for the edit @Fred I always wondered how you do this. $\endgroup$
    – Giovanni
    Dec 10 '21 at 17:29
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    $\begingroup$ Serious users of GNSS navigation, like hikers or bicyclists, focus on the altitude too. They are aware of the fact the Earth geoid deviates from the reference ellipsoid WGS84, used in the GNSS. Particularly, users in the Central Europe have to subtract about 60 metres from the raw GNSS altitude, what is usually done by the correction aware application. $\endgroup$
    – Poutnik
    Jan 10 at 7:33

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