Great-Circle Measurement — Tool for Shortest Earth Distance Which representation is most useful for measuring the shortest distance and route between two places on Earth’s surface?

Introduction / Context:
On a sphere, the shortest path between two points lies along a great circle. Flat maps distort distances and directions to varying degrees. Selecting the correct tool to visualise true shortest routes is fundamental to navigation and geography.

Given Data / Assumptions:

• Earth is approximately an oblate spheroid; for route planning it is treated as a sphere.
• Different map projections preserve different properties (area, shape, distance, direction), but not all simultaneously.
• We need the most faithful depiction for great-circle distance.

Concept / Approach:

A globe preserves Earth’s geometry without projection distortion, so great circles can be traced directly to yield shortest routes. Atlas, thematic, and wall maps are flat projections; while some projections can represent great circles as straight lines (e.g., gnomonic) or preserve distances from a point, they still require interpretation and conversion. For straightforward accuracy, the globe is superior.

Step-by-Step Solution:

Define shortest path: great-circle arc on a sphere.Identify medium without distortion: three-dimensional globe.Evaluate alternatives: flat maps introduce projection error.Choose “Globe.”

Verification / Alternative check:

Airline routes drawn on globes follow great-circle arcs; on Mercator maps they appear curved because of projection effects, confirming the globe’s fidelity for distance.

Why Other Options Are Wrong:

Atlas/Thematic/Wall maps: Useful, but projection choice limits direct shortest-distance measurement without corrections.

Common Pitfalls:

Assuming a straight line on any map is always the shortest path; this depends on the projection and is generally untrue outside special cases.

Final Answer:

Globe