The intersection points of parallels are truly spaced along which meridian?

• A. Central Meridian
• B. Equator
• C. Prime Meridian
• D. 90 degrees East Meridian

Answer: (A)

Parallels and meridians form a graticule, and a map projection distorts distances differently as you move away from a certain reference line. The central meridian is the reference in many projections where the scale is true (scale factor = 1), so the spacing between successive parallels when measured along that line matches the actual ground distance. That means the intersection points of parallels with the central meridian are truly spaced. Along other meridians, distortion alters the spacing, so the intersections aren’t true to ground distances. The equator or any fixed longitude like a prime meridian isn’t inherently the line of true spacing unless it happens to be the projection’s central meridian.