THE Mollweide Projection – also called Aitoff projection – is a cartographic projection elaborated in the year 1805 by the German astronomer and mathematician Karl Mollweide (1774-1825), widely used for the elaboration of world maps today.
It is a cylindrical projection, that is, it is a type of projection elaborated as if the Earth had been involved in a cylinder, projecting its parallels and meridians on it, being then unrolled and represented in a flat.
The projection elaborated by Mollweide is of the equivalent type, that is, it conserves the size of the areas, but alters their shapes. Thus, as with all cartographic projections, it presents some distortions, which increase as they move away from the central point represented (note the figure at the beginning of the text).
Karl Mollweide – well known not only for his projection, but also for his great achievements in the field of mathematical equations – was looking for a way to correct the Mercator projection, since this was very useful for navigations, but not recommended for analysis of the continents because it changes their scales.
So he constructed a projection in which the parallels were straight lines and the meridians were curved lines, as opposed to what Mercator had done, in which the lines and parallels were equally straight. In the work carried out by Mollweide, the Earth gained an elliptical projection with an exact proportion to the real area of the terrestrial sphere, with the poles being flatter and the central zones being more exact.
In addition to being quite widespread in the preparation of world maps, this projection was also widely used in thematic maps on the comparison of data between continents (population, income, arable areas, etc.), where the main area was highlighted in the central position and the places used for comparison were placed in the zones sides of the plane.
By Rodolfo Alves Pena
Graduated in Geography
Source: Brazil School - https://brasilescola.uol.com.br/geografia/projecao-mollweide.htm
