Which of the following characteristics is true of the Mercator projection?

• A. Straight lines representing the true direction
• B. The projection preserves distances along great circles
• C. Latitude lines are equally spaced
• D. It projects onto a sphere with no distortion

Answer: (A)

Mercator projection is a map that keeps angles and shapes locally intact, which is what makes it especially useful for navigation. Because it preserves direction locally, a straight line on the map corresponds to a path of constant bearing (a constant compass direction) on the Earth. This is why you can plot a course by drawing a straight line on the map and follow that line while steering at the same angle—the direction remains true along the route.

However, this comes at the cost of other distortions. Distances and areas are not preserved; great-circle distances won’t map to straight lines, and the scale grows with latitude, so parallels spread farther apart toward the poles. Also, latitude lines are not equally spaced on the map—the spacing increases as you move away from the equator. So, the statement about straight lines representing the true direction captures the essential navigational property of the Mercator projection.