Astronomy 123 Basics   Temperature Scales 

There are three temperature scales in common usage: 

The Fahrenheit Scale: 
• we are most familiar with this one
• water freezes at 32 degrees F.
• water boils at 212 degrees F.
• when we cool to the absolute lowest temperature we reach -459 degrees (this is referred to as Absolute Zero)

The Celsius Scale:
• water freezes at 0 degrees C.
• water boils at 100 degrees C.
• Absolute Zero is at -273 degrees C.

The Kelvin Scale
• Absolute Zero is 0 K
• a temperature change of 1 degree K is the same as a temperature change of 1 degree C.
• water freezes (or melts) at 273 K
• water boils at 373 K

The Kelvin is scale is the more useful scale for our course since it refers to Absolute Zero in a direct way.