Experiment 02 · Size & shape

Same Earth. Different sizes.

Use equal-area circles to see why a familiar world map can give an unfamiliar impression of size.

10–15 minutes · No preparation needed

Before you unfold

Will circles enclosing equal areas on Earth still have equal areas on every flat map?

Try it yourself

Open the experiment to see Mercator and Mollweide together. The pale circles enclose equal areas on Earth.
Unfold Earth. Within each map, compare circles near the equator with circles farther north or south.
Below the maps, move the orange sample’s latitude slider from 0° to 60°. Read the local area scale for each projection.
Change the second map from Mollweide to Gall–Peters. Compare the areas and shapes of the circles again.

Open experiment ↗

Opens in another tab so you can keep these steps nearby. Use the slider to explore at your own pace.

What did you notice?

What happens to the pale circles’ areas in Mercator? What happens in Mollweide?
At 60° latitude, record the local area scale for Mercator and Mollweide. What does that comparison tell you?
Mollweide and Gall–Peters both preserve relative area. Do they preserve every shape too? Use an observation as evidence.

Reveal the explanation

Equal-area maps preserve proportions of area, but can stretch shapes. Mercator preserves local angles while enlarging areas toward the poles. Choose a projection for the question you want to answer.

Compare proportions within each map, not pixel sizes between panels: the explorer fits projections independently. The finite circles are visual samples; the numerical readout describes local area scale. Neither equal-area projection is the only correct world map.

Sources & further reading

Original MapStudy activities, informed by these projection references. Country boundaries in the explorer come from Natural Earth. The animation illustrates a transition; its intermediate shapes are not separate named projections.