Lindblad, Bertil (1895-1965)

Swedish astronomer. He demonstrated the rotation of our Galaxy. He went on to stipulate that the speed of rotation of the stars in the Galaxy was a function of their distance from the centre (the ‘differential rotation theory’).

Lindblad was born in Örebro and studied at Uppsala. He was appointed director of the new Stockholm Observatory 1927, and was responsible for its transfer to a new site at Saltsjöbaden. He was also professor of astronomy at the Royal Swedish Academy of Sciences; president of the International Astronomical Union 1948-52; president of the International Council of Scientific Unions; and president of the Council of the European Southern Observatory, which he helped to found.

His early work was on the colour of stars and on spectroscopic luminosity criteria, but later he turned to stellar dynamics and was one of the first to suggest that the Galaxy was rotating.

Dutch astronomer Jacobus Kapteyn had proposed that the Solar System lay near the centre of the Galaxy, whereas US astronomer Harlow Shapley believed that the centre of the Galaxy was some 50,000 light years away in the direction of the constellation Sagittarius. Lindblad suggested that the two streams of stars Kapteyn had observed could in fact represent the rotation of all the stars in our Galaxy in the same direction, around a distant centre; he thus confirmed Shapley's hypothesis.