On this day…
Anders Celsius, a Swedish astronomer, physicist, and mathematician, was born on November 27, 1701. Celsius is best known for the temperature scale that bears his surname, the Celsius temperature scale.
Anders Celsius chose to pursue a career in science at an early age, as he was the son of an astronomy professor and the grandson of a mathematician and astronomer. A talented mathematician from an early age, Celsius studied at Uppsala University, where his father taught. Celsius would later become a professor of astronomy at Uppsala University, as well.
In an effort to build an astronomical observatory in Sweden, Celsius spent his time from 1732 – 1734 traveling around Europe, visiting most of the major European observatories. In 1736, Celsius was involved in an expedition to Lapland (the northernmost part of Sweden) to measure a degree of latitude. At the time, there was debate between astronomers regarding the actual shape of the earth. The idea was that length of a degree along a meridian in Lapland would be compared to the length of a degree near the equator. The expedition and research confirmed that the earth experiences flattening at the poles.
The expedition won Celsius respect from the Swedish government, and was an integral part of the government’s decision to donate the resources required to construct a modern observatory in Uppsala. The Uppsala Astronomical Observatory was founded in 1741. During his research at the observatory, Celsius became one of the first astronomers to attempt to measure the intensity of starlight using a tool other than the human eye.
Celsius was also the first to perform experiments with the goal of defining an international temperature scale. His tests included the impact that atmospheric pressure has on the freezing and boiling points. He proposed the Celsius temperature scale (originally called centigrade, Latin for “hundred steps”) in a paper to the Royal Society of Sciences in Uppsala. The thermometer that Celsius designed was calibrated for a freezing point of water of 100° and a boiling point of 0°. This scale was later reversed by Carl Linnaeus in 1745, a year after Anders Celsius’ death.
Anders Celsius became secretary of the Royal Society of Sciences in Uppsala in 1725, a position that he held until his death from tuberculosis in 1744.