150th anniversary of Quetelet’s death

150 years ago, on February 17, 1874, Adolphe Quetelet, founder and first director of the Royal Observatory of Belgium, passed away. He was one of the best-known Belgians of his time. A keen statistician, he is best known as the inventor of the Quetelet index, better known today as the BMI (Body Mass Index). Books have been written about this influential figure. He founded our Observatory in 1826 and was permanent secretary to the Royal Academy for almost 50 years.

He also organized the first parliamentary elections and population censuses in the new Belgium. Among other things, he conceptualized the mortality rate, a variable used extensively during the COVID-19 epidemic. He sat on the founding committees of the Jardin Botanique, the ULB, the Cercle Gaulois and many other entities. He was also co-founder and first president of the International Conference on Marine Meteorological Observations, having developed a scientific method for unifying meteorological parameters after decades of research.

His most important discovery was the relationship between the Gauss curve and certain natural phenomena. Gauss had perfected his mathematical model for analyzing astronomical data. When Quetelet visited Göttingen, Gauss gave him this formula for his calculations. Quetelet also used this formula to analyze the health of soldiers in the Belgian army. It was this same inspiration that made him the founder of social statistics.

Quetelet was a great man for Belgium and for science and statistics, but for us, he is above all the founder of the Observatory.

Thanks to him, the Royal Observatory is today an official observatory in Belgium, the only official observatory to date. This happened almost 200 years ago, in 1826, which makes 2026 a special year, full of festivities and special events. Stay tuned!