Milutin Milanković

Milutin Milanković was born in 1879 in Dalj, then part of Austria-Hungary, into a Serbian family. He trained as a civil engineer in Vienna, specialising in reinforced-concrete structures, but his intellectual ambition was always astronomical: he wanted a mathematical climatology — a theory that could predict, from first principles, the amount of sunlight reaching each latitude of the Earth in each season, at any point in the geologic past.

He took up a professorship of applied mathematics at the University of Belgrade in 1909 and began the long calculation in 1912. When WWI broke out in 1914, Milanković — a Serbian citizen caught in Austria-Hungary while visiting his home village on his honeymoon — was arrested and interned as a prisoner of war in Budapest. Through the intervention of colleagues, he was granted working access to the library of the Hungarian Academy of Sciences, and he spent the four years of his internment computing the insolation curves by hand. His 1920 Théorie mathématique des phénomènes thermiques produits par la radiation solaire laid out the framework; the 1941 Canon of Insolation completed it.

His theory was initially received with scepticism — the paleoclimate data of the 1940s could not yet test it. Vindication came decades after his death, when deep-sea sediment cores and Antarctic ice cores from the 1970s onward revealed glacial-interglacial cycles whose spectrum matched Milanković's orbital frequencies almost exactly. The three cycles — eccentricity (~100 kyr), obliquity (~41 kyr), and precession (~23 kyr) — are now known as Milankovitch cycles, and they are the astronomical foundation of modern paleoclimatology.