Celsius is a familiar name to much of the world since it represents the most widely accepted scale of temperature. It is ironic that its inventor, Anders Celsius, the inventor of the Celsius scale, was primarily an astronomer and did not conceive of his temperature scale until shortly before his death.

The son of an astronomy professor and grandson of a mathematician, Celsius chose a life within academia. He studied at the University of Uppsala where his father taught, and in 1730 he, too, was given a professorship there. His earliest research concerned the aurora borealis (northern lights), and he was the first to suggest a connection between these lights and changes in the earth's magnetic field.

Celsius traveled for several years, including an expedition into Lapland with French astronomer Pierre-Louis Maupertuis (1698-1759) to measure a degree of longitude. Upon his return he was appointed steward to Uppsala's new observatory. He began a series of observations using colored glass plates to record the magnitude of certain stars. This constituted the first attempt to measure the intensity of starlight with a tool other than the human eye.

The work for which Celsius is best known is his creation of a hundred-point scale for temperature, although he was not the first to have done so since several hundred-point scales existed at that time. Celsius' unique and lasting contribution was the modification of assigning the freezing and boiling points of water as the constant temperatures at either end of the scale. When the Celsius scale debuted in 1747 it was the reverse of today's scale, with zero degrees being the boiling point of water and one hundred degrees being the freezing point. A year later the two constants were exchanged, creating the temperature scale we use today. Celsius originally called his scale centigrade (from the Latin for "hundred steps"), and for years it was simply referred to as the Swedish thermometer . In 1948 most of the world adopted the hundred-point scale, calling it the Celsius scale.