ASTRONOMY FUNDAMENTALS - Chapter 7, Exercise 2 Solution
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Scaling the Sun's Distance Against the Galaxy's Diameter

PROBLEM
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Using the Milky Way's real diameter (~87,400 light-years) and the Sun's
real distance from the galactic center (~27,140 light-years), calculate
how many times the Sun's own distance from the center would need to be
laid end-to-end to span the galaxy's full diameter.

SOLUTION
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Divide the galaxy's real diameter by the Sun's real distance from the
center:

    Number of lengths = Galaxy diameter / Sun's distance from center
    Number of lengths = 87,400 ly / 27,140 ly
    Number of lengths ≈ 3.22

ANSWER: The Sun's own distance from the galactic center would need to
be laid end-to-end approximately 3.22 times to span the Milky Way's
full real diameter.

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WHY THIS WORKS AS AN ANSWER

This is a straightforward real ratio calculation: dividing the whole
quantity (the galaxy's total diameter) by the smaller reference length
(the Sun's own distance from the center) gives how many of those
smaller lengths fit into the larger one. The result, just over 3,
provides a genuinely useful, concrete sense of scale: the Sun is not
sitting anywhere near the galaxy's outer edge, but it is also
noticeably closer to the center than to the true edge of the visible
disk - roughly consistent with the chapter's own description of the
Sun sitting on the "inner rim" of the Orion Arm, meaning still a
meaningful distance out from dead center, but well within the
galaxy's own real overall span.