Why do cartographers cut the world like an orange peel?
The Interrupted Goode Homolosine shows why a visible seam can be more honest than stretching.
An orange peel cannot be flattened without a decision
Every flat map must stretch, squeeze or cut the sphere. A rectangular map usually hides that decision at its edges, where distortion is greatest. The Goode homolosine shows it openly: it cuts the world where the cuts get in the way of reading the map least.
Two projections in one
J. Paul Goode of the University of Chicago developed the projection in 1923. He joined two equal-area projections: the sinusoidal between 40°44' north and south, and the Mollweide farther from the Equator. The boundary is not arbitrary. On those parallels both projections have the same scale, so they can be joined without a jump. Hence the name: “homolosine” combines the old name of the Mollweide projection (homolographic) with the name of the sinusoidal.
Which is larger in reality: Africa or Greenland?
Both parts are equal-area, so the whole map keeps the proportions of areas. The shapes of continents are still distorted, especially far from the central meridians.
Why use lobes?
In the interrupted version the map has six central meridians, one in each lobe. Rather than letting distortion build up across one sheet, the map starts again at each center and moves the discontinuity into the seams. In the classic layout the seams cross the oceans so that the land stays whole. Goode intended his projection to be interrupted from the start, and it is almost always shown that way.
Where does this map work well?
According to the USGS album of map projections, the Goode homolosine was used on many world maps, especially in Rand McNally's Goode's Atlas. In the 1990s its interrupted form was chosen for global 1 km AVHRR satellite datasets. As D. R. Steinwand described in a 1994 paper, an interrupted equal-area map is both attractive and practical for analyzing such data.
An interrupted map is therefore well suited to comparing what covers the surface: forests, deserts, crops or population density. It is poor for routes and ocean currents that cross its seams.
Three ways to place the seams
In the lab, switch between “Protect land”, “Protect oceans” and “No seams”. The ocean version arranges the lobes so that the seams cross land and the oceans stay whole. The continuous version restores a single sheet at the cost of greater distortion at the edges. Compare it with Equal Earth, which keeps area proportions without cutting the map.