A second of latitude near the poles is approximately a foot longer than a second of latitude near the equator. How should this statement be evaluated?

• A. It is shorter by about a meter
• B. False
• C. True
• D. It is shorter by a few inches

Answer: (C)

As you move from the equator toward the poles, the distance covered by a fixed angular change in latitude increases because the Earth is an oblate spheroid and meridians bow outward toward higher latitudes. A second of latitude is a tiny arc along a meridian, and its length is set by the local meridional radius of curvature. That radius is smaller near the equator and becomes larger toward the poles, so each second of latitude represents more ground at higher latitudes.

In numbers, a second of latitude is about 30.9 meters near the equator and a bit longer toward the poles—on the order of a few centimeters longer per second (roughly several centimeters, not a full foot). So the statement that a second of latitude near the poles is longer than near the equator is true in direction, and the approximate magnitude is consistent with the trend, even though the exact difference is smaller than a foot.