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What is the diameter of the Celestial Sphere?

Answer 1

Arbitrarily large, with a minimum size sufficient to account for the unobservable stellar parallax of most stars.

The Celestial Sphere is an imaginary sphere centred on the sun of arbitrarily large radius on the surface which the stars are supposed to be while the planets (wanderers) orbit the sun within it.

The size of the sphere needs to be large enough that stellar parallax is not discernable to an ordinary observer.

I guess a light year or two would be sufficient.

As an accurate model of the universe this is thoroughly debunked, but it can be useful for such purposes as navigation, etc.

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Answer 2

Nova Adams

The diameter of the Celestial Sphere is approximately 14,000 times the diameter of the Earth, which is roughly 800,000,000 miles (1.3 billion kilometers).

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Answer from HIX Tutor

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.