Anders Celsius. Portrait of the Swedish astronomer Anders Celsius (1701-1744). Celsius was the first to associate the aurora borealis with changes in the earth's magnetic field. In 1730 he became professor of astronomy at Uppsala, and by 1740 he was in charge of the large new observatory there. His best known achievement was his temperature scale, which divided the temperature difference between the boiling point and freezing point of water into an even hundred degrees. He first described this in 1742 when he placed the boiling point at zero and the freezing point at 100 degrees. The following year this was reversed. This scale is used by scientists everywhere.