The story of Mollweide · 1805
Mollweide
Room for the whole world, with areas in proportion.
Explore Mollweide →The stronger line marks the equator.
Why this map exists
Room for the whole world, with areas in proportion.
Represent the whole world with correct proportions of area. This makes it useful for comparing the geographic extent of things such as habitats or land cover.
How the idea developed
1805
An equal-area ellipse
Carl Brandan Mollweide presented the projection in 1805. Its elliptical outline is twice as wide as it is high, with the geographic poles at the top and bottom in the classic orientation.
USGS Astrogeology · Mollweide reference1857
An idea returns
Jacques Babinet reintroduced the projection in 1857 as the homalographic projection. Its later influence shows that a useful mapping idea can gain attention long after its first appearance.
Snyder · USGS, Map projections: A working manualEarly 20th century
A starting point for other projections
J. Paul Goode experimented with interrupted Mollweide maps in 1916 and later combined Mollweide with the sinusoidal projection to make the Homolosine. Cuts offered a way to reduce distortion in selected regions while retaining equal area.
Snyder · USGS, Map projections: A working manual
What you gain. What changes.
What stays true
Relative area across the map. Regions of equal area on Earth occupy equal areas within the same Mollweide map.
What changes
Shapes stretch and directions change, particularly toward the outer parts of the map. In the classic view, latitude lines are straight and most longitude lines curve.
Projection properties: PROJ · Mollweide
A common misunderstanding
Equal area does not mean every distance, angle, or shape is correct. Mollweide and Gall–Peters can both preserve area while looking very different.
What changes in a country-centered view?
These historical descriptions refer to the classic orientation. MapStudy can rotate the projection’s reference frame so the place facing you becomes the center. The projection still preserves its defining property, but references to the equator, poles, and navigation do not transfer unchanged to the rotated view. Geographic latitude and longitude lines may curve.
The unfolding animation illustrates a mathematical transition. The intermediate shapes are not separate named projections, and Earth is not physically peeled into this map.
See the idea for yourself
Can circles change shape without changing area?
- Unfold Earth into Mollweide with the equal-area circles visible.
- Compare pale circles near the center and near the edge. Their outlines change, but their areas stay equal within the map.
- Switch to Gall–Peters. Find another way to preserve areas while changing shapes.
Opens in another tab so you can keep the steps nearby.
Sources & further reading
The history and explanations are original MapStudy writing based on the references linked above. Uncertain origins are identified as such. We credit the projection’s creators and later advocates; MapStudy’s contribution is this interactive learning experience.
Our diagrams use the same spherical equations as the explorer. They show geographic grids, not historical source material.