Chemistry Blog - Anders Celsius

Anders Celsius, a Swedish astronomer born in Uppsala, Sweden, contributed to the world of science immensely. He was born in 1701 into a family of professors, his grandfathers being Magnus Celsius and Anders Spole. Magnus was a mathematician, and Spole was an astronomer. Nils Celsius, Anders Celsius’s father, was a professor in astronomy in the University of Uppsala. This is where Anders studied and followed his father’s footsteps by being appointed an astronomy professor at the young age of 29.

At that time, observatories were not built in Sweden, so Anders traveled around the world in 1732 to the most paramount observatories in that time period. His trip lasted four years, and he worked with several eminent astronomers of the 18^th century in Germany, Italy, and France. One of the benefits from this interaction is that Anders published a collection in Nuremberg, Germany of his 316 observations about the aurora borealis, also known as the Northern Lights. They were formulated by him and other astronomers in 1733.

For a long time, there was constant dispute on what shape the Earth has always been. Isaac Newton proposed that the Earth was flattened at the poles while France felt the Earth was elongated at those locations. Expeditions to Ecuador and northern Sweden were arranged to measure the degree of longitude in each spot for comparison. Anders took part in the journey to Lapland in northern Sweden with the French astronomer Pierre Louis de Maupertuis in 1736. Celsius was the only professional astronomer on the team. The measurements the two expeditions brought back confirmed Newton’s theory of the Earth being flattened at the poles. Finally! Solid proof was found at last on the actual shape of the Earth. Thereafter, no more disputes occurred, and this fact was accepted worldwide. The definition of Earth as being a flattened ellipsoid is still acknowledged today.

After returning from the journey, Celsius convinced Swedish authorities to make a budget for an observatory in Uppsala. The Celsius Observatory was constructed in 1741 and was the first and most modern observatory in Sweden. Anders was appointed director of this observatory. He used it to research eclipses and be the first to measure the magnitude, or brightness, of stars using equipment other than the human eye. By utilizing glass plates, Anders compared magnitudes of stars by finding out how many plates it required to extinguish the stars’ light. With these observations, he published catalogues of a total of 300 stars using his own photometric system. His research proved that Sirius is the brightest star in the sky, requiring twenty-five glass plates to douse the light. Also after building the observatory, Celsius was the first to notice that auroras affect compass needles and the Earth’s magnetic field. This discovery helped in the progress of research regarding these intriguing Northern Lights.

Without a doubt, the observations that made Anders Celsius most famous were the ones concerning the temperature scale. In 1742, he recommended dividing the thermometer into 100 degrees. Celsius was not the first to make a hundred-point scale, but he was the only one to propose that 0 degrees, at a certain atmospheric pressure, was the boiling point of water and 100 degrees was its freezing point. The scale was reversed to 100 degrees being the boiling point and 0 degrees being the freezing point after Anders’s death in 1744. For a few years, Anders's measurements were known as the Swedish thermometer until it was accepted all over the world. It was then renamed the Celsius scale. This thermometer thoroughly changed the everyday lives of humans. Now, everyone can find the temperature of the outside air accurately and can be prepared for the day’s weather. The Celsius scale has greatly helped in advances in meteorology, making several measurements for vital weather research easier to understand and work with. All in all, Anders Celsius contributed substantially to the scientific society, and his laudable research thoroughly modified the science world.