He founded the Uppsala Astronomical Observatory in 1741, and in 1742 proposed (an inverted form of) the Centigrade temperature scale which was later renamed Celsius in his honour.

[5][6] In 1730, Celsius published the Nova Methodus distantiam solis a terra determinandi (New Method for Determining the Distance from the Earth to the Sun).

His research also involved the study of auroral phenomena, which he conducted with his assistant Olof Hiorter, and he was the first to suggest a connection between the aurora borealis and changes in the magnetic field of the Earth.

[4][page needed] In 1738, he published the De observationibus pro figura telluris determinanda (Observations on Determining the Shape of the Earth).

Celsius's participation in the Lapland expedition won him much respect in Sweden with the government and his peers, and played a key role in generating interest from the Swedish authorities in donating the resources required to construct a new modern observatory in Uppsala.

[3] He made observations of eclipses and various astronomical objects and published catalogues of carefully determined magnitudes for some 300 stars using his own photometric system (mean error=0.4 mag).