Celsius was born at Ovanåker in Sweden. He was professor of astronomy at Uppsala University from 1730 to 1744, but travelled from 1732 to 1735 visiting notable observatories in Germany, Italy and France.
At Nuremberg he published in 1733 a collection of 316 observations of the aurora borealis made by himself and others over the period 1716–1732. In Paris he advocated the measurement of an arc of the meridian in Lapland, and in 1736 took part in the expedition organized for that purpose by the French Academy of Sciences.
Celsius was one of the founders of the Uppsala Astronomical Observatory in 1741. He is best known for the Celsius temperature scale, first proposed in a paper to the Royal Swedish Academy of Sciences in 1742.
He died of tuberculosis in Uppsala.
- "Nova Method us distantiam solis a terra determinandi" (1730)
- "De observationibus pro figura telluris determinanda" (1738)