Galileo thermometer

The density of a liquid varies with the temperature. When the temperature of a liquid increases, its density decreases and so the buoyancy of the liquid increases. There are liquid-filled bubbles in the container, which have been carefully adapted to the density of the precise temperature they show. The temperature is shown on the ball that is floating at the very bottom.

The thermometer was named after Galileo Galilei who experimented with the density of liquids at different temperatures at the start of the 17th century.

Where can you see this in everyday life?

When water is heated in the atmosphere, its density changes and it rises as water gas. The water sticks to small particles in the atmosphere. When the water cools down, water droplets are created that grow and get bigger. Eventually, when pressure is low they will fall down in liquid form as water, or in solid form as snow or hail.

Sustainable development

A thermometer is important if you want to save energy. When we heat our houses, we want a nice indoor temperature. A good indoor temperature is measured as 20 degrees Celsius on a normal thermometer. We can save heating energy with help from well-insulated houses and energy efficient windows that keep the heat where it should be – inside the house.