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Celsius (1701)

Anders Celsius (1701)

image of Anders Celsius

Source: Olof Arenius, Wikimedia Commons (Public Domain)

Celsius was born in 1701 in Sweden. He succeeded his father as professor of astronomy at the University of Uppsala in 1730. It was there that he built Sweden's first observatory in 1741. One of the major questions of that time was the shape of the Earth. Isaac Newton had proposed that the Earth was not completely spherical, but rather flattened at the poles. Cartographic measuring in France suggested that it was the other way around - the Earth was elongated at the poles. In 1735, one expedition sailed to Ecuador in South America, and another expedition traveled to Northern Sweden. Celsius was the only professional astronomer on that expedition. Their measurements seemed to indicate that the Earth actually was flattened at the poles.

image of Celsius' thermometer
image of various thermometers

Celsius was not only an astronomer, but also a physicist. He and an assistant discovered that the aurora borealis had an influence on compass needles. However, the thing that made him famous is his temperature scale, which he based on the boiling and melting points of water. Celsius' fixed scale for measuring temperature defines zero degrees as the temperature at which water freezes, and 100 degrees as the temperature at which water boils. This scale, an inverted form of Celsius' original design, was adopted as the standard and is used in almost all scientific work.

Anders Celsius died in 1744, at the age of 42. He had started many other research projects, but finished few of them. Among his papers was a draft of a science fiction novel, situated partly on the star Sirius.