GEODESY — Earth’s shape and diameters Statement: The polar diameter is ____ compared to the equatorial diameter of Earth. Choose the correct comparison.

Introduction / Context:
Earth is not a perfect sphere. Due to rotation, it bulges at the equator and flattens slightly at the poles, producing an oblate spheroid. Recognizing the relationship between polar and equatorial diameters is foundational in geography and Earth science.

Given Data / Assumptions:

• Earth rotates about its axis, causing centrifugal effects strongest at the equator.
• Equatorial radius exceeds polar radius by a small amount.
• We compare diameters (twice the radii).

Concept / Approach:
Centrifugal force from rotation opposes gravity most at the equator, allowing Earth’s surface to bulge outward slightly. This increases the equatorial radius and diameter. At the poles, centrifugal effect is minimal, so the polar radius is smaller. Thus the polar diameter is less than the equatorial diameter.

Step-by-Step Solution:
Recall typical values: equatorial diameter ≈ 12,756 km; polar diameter ≈ 12,714 km.Compare: polar is smaller by ~42 km.Therefore, the correct comparative word is “less.”

Verification / Alternative check:
Global positioning and satellite geodesy confirm Earth’s flattening (ellipticity), quantified by flattening f ≈ 1/298.257, consistent with a slightly smaller polar diameter.

Why Other Options Are Wrong:
More/Equal — contradict measurements.Cannot be compared — they can; both are measurable.Twice as large — grossly incorrect; differences are small, not a factor of two.

Common Pitfalls:
Confusing radius with diameter or overestimating the bulge magnitude. The difference is modest (~0.3%).

Final Answer:
less