Swedish astronomer who developed the idea behind the temperature scale that was named after him. He founded the Uppsala Astronomical Observatory in 1741.
He became the first to posit a direct correlation between the Earth's changing magnetic fields and the aurora borealis.
His first name for the temperature scale was centigrade, which comes from the Latin for hundred steps.
His father, Nils Celsius, was an astronomy professor, and his grandfather, Magnus Celsius, was a mathematician.
He participated in a French scientific expedition, which confirmed Isaac Newton's theory that the Earth flattened out around the poles.