Celsius

Hot and Cold

Winter is coming to the northern hemisphere, and with it, talk of central heating, gloves and scarves, snowfall, and record low temperatures. Monitoring temperatures is part of our everyday life -- whether we're talking about the weather, our bodies, central heating, or cooking.

In the United States, we typically measure temperature in degrees Fahrenheit. But in other countries, such as England, you'll get the weather forecast in degrees Celsius. Recipes will advise you to bake a pie at 205Ñ"C and not 400Ñ"F. In fact, the Celsius scale is the most commonly used temperature scale in the world. This week, we have special cause to wonder about the history of this scale, because November 27 is the 300th anniversary of the birthday of the man who invented it.

Anders Celsius was born in Sweden in 1701. His parents didn't know that their son's work would one day make their family name an everyday word used by millions of people around the world.

Meet Professor Celsius

The world Anders lived in was very different than the world we know. Much of the knowledge that we now take for granted -- such as the motion of Earth with respect to the Sun and planets -- was only beginning to be understood then. In Europe, radical and brilliant scientists, such as Galileo and Sir Isaac Newton, had been developing new and revolutionary ways of understanding the workings of the world and the universe. The era was known as "the Enlightenment," and it was a good time for someone of Anders's ability to be working in the field of science.

Anders's talent came from his family of academics: one of his grandfathers was a mathematician and the other an astronomer, and his father, Nils, was a professor of astronomy. As a child, Anders showed a natural flair for mathematics, but he developed a keen interest in astronomy and became a professor at the age of 29. So, how did a clever astronomer come to develop a temperature scale?

The answer lies with the weather. When making observations of the night sky, Anders monitored the weather conditions, including the temperature. At the time there were a lot of different kinds of thermometers with different scales -- by the time Anders started working on the problem of temperature measurement, around 35 different scales existed. (Compare this number with today, when three main scales are in use -- Celsius, Fahrenheit, and Kelvin.) It is thought that Anders may have realized the need to have an international standard, and