Milutin Milanković (sometimes anglicised as Milutin Milankovitch; Serbian Cyrillic: Милутин Миланковић, pronounced [milǔtin milǎːnkoʋitɕ]; 28 May 1879 – 12 December 1958) was a Serbian mathematician, astronomer, climatologist, geophysicist, civil engineer, university professor, popularizer of science and academic.

Milanković gave two fundamental contributions to global science. The first contribution is the "Canon of the Earth's Insolation", which characterizes the climates of all the planets of the Solar System. The second contribution is the explanation of Earth's long-term climate changes caused by changes in the position of the Earth in comparison to the Sun, now known as Milankovitch cycles. This partly explained the ice ages occurring in the geological past of the Earth, as well as the climate changes on the Earth which can be expected in the future.

He founded planetary climatology by calculating temperatures of the upper layers of the Earth's atmosphere as well as the temperature conditions on planets of the inner Solar System, Mercury, Venus, Mars, and the Moon, as well as the depth of the atmosphere of the outer planets. He demonstrated the interrelatedness of celestial mechanics and the Earth sciences and enabled a consistent transition from celestial mechanics to the Earth sciences and transformation of descriptive sciences into exact ones.

A distinguished professor of applied mathematics and celestial mechanics at the University of Belgrade, Milanković was a director of the Belgrade Observatory, member of the Commission 7 for celestial mechanics of the International Astronomical Union and vice-president of Serbian Academy of Sciences and Arts. Beginning his career as a construction engineer, he retained an interest in construction throughout his life, and worked as a structural engineer and supervisor on a series of reinforced concrete constructions throughout Yugoslavia. He registered multiple patents related to this area.

Milutin Milanković was born in the village of Dalj, a settlement on the banks of the Danube in what was then part of Austro-Hungarian Empire. Milutin and his twin sister were the oldest of seven children raised in a Serb family. Their father was a merchant, landlord and a local politician who died when Milutin was seven. As a result, Milutin and his siblings were raised by his mother, grandmother, and an uncle. His three brothers died of tuberculosis at a young age. As his health was fickle, Milutin received his elementary education at home, learning from his father Milan, private teachers, and from numerous relatives and friends of the family, some of whom were renowned philosophers, inventors, and poets. He attended secondary school (realgymnasium) in nearby Osijek, completing it in 1896.

In 1896, he moved to Vienna to study Civil Engineering at the TU Wien and graduated in 1902. In his third year of studies, Milanković found more free time for wider education. He paid his full attention to the monumental buildings of Vienna, thereby gradually understanding all the beauty of architecture. He also visited Viennese museums and galleries, after which he became an admirer of Raphael's Madonna del Prato. He showed great interest in the Vienna Opera, which he visited regularly. In addition, he devoted his attention to learning the French language by taking private lessons and attending summer French language course in Geneva in 1899. During a stay in Switzerland, Milankovitch visited the Institute for the Testing Building Materials in the Polytechnic in Zurich. In the Viennese ″Café Elisabethbrücke″, which was not fashionable but served only for reading, he spent an hour or two daily reading numerous newspapers and magazines. The professor of the science of the building bridges, Johann Brik [de], the top expert of Viennese Mechanics of that time, taught the most important subject of the fifth school year. In Brikʼs teaching, young Milankovitch found strong inspiration for later scientific work, as he describe it: ″Brikʼs lectures were very interesting to me. His mastering of mathematical analysis was excellent and would constantly apply it in his lectures. To a good mathematician it gives certain independence and freedom in solving problems.″

After graduating and spending his obligatory year in military service, Milankovitch borrowed money from an uncle to pay for additional schooling at TU Wien in engineering. At age twenty-five, his PhD thesis was entitled Contribution to the Theory of Pressure Curves (Beitrag zur Theorie der Druckkurven) and its implementation allowed assessment of pressure curves' shape and properties when continuous pressure is applied, which is very useful in bridge, cupola and abutment construction. His thesis was successfully defended on 3 December 1904; examination committee members were Johann Emanuel Brik, Josef Finger, Emanuel Czuber and Ludwig von Tetmajer. He then worked for an engineering firm in Vienna, using his knowledge to design structures.

At the beginning of 1905, Milanković took up practical work and joined the firm of Adolf Baron Pittel Betonbau-Unternehmung in Vienna. He built dams, bridges, viaducts, aqueducts, and other structures in reinforced concrete throughout Austria-Hungary. So Milankovitch verified his theoretical knowledge and design tools on numerous reinforced concrete structures that he built during his engineering service in Vienna. Milankovitch participated with structural calculations and practical work in the construction of a total of ten hydroelectric power plants. Among them, the most notable is the one built in Sebeș (present-day Romania) in the Transylvania region. Milankovitch's specific task was to design a reinforced concrete aqueduct 1200 m long, which would bring water above the turbines of the city's hydroelectric power plant. After that, he was engaged in the construction of the viaduct in Hirschwang (Semmering) in 1906 and in Pitten near Vienna in 1907.