A comparison of the Kelvin, Celsius, and Fahrenheit temperature scales. The freezing point of water is 273 kelvins; water boils at 373 kelvins. The zero point on the Kelvin scale is absolute zero, the coldest possible temperature.
Click on image for full size
Original artwork by Windows to the Universe staff (Randy Russell).
Kelvin Temperature Scale
The Kelvin scale is a temperature scale that is often used in astronomy and space science. You are probably more familiar with the Celsius (or Centigrade) scale, which is part of the metric system of measures, and the Fahrenheit scale, which is used in the English system.
The Kelvin scale is similar to the Celsius scale. Zero degrees is defined as the freezing point of water in the Celsius system. However, the zero point in the Kelvin scale is defined as the coldest possible temperature, known as "absolute zero". Absolute zero is –273.15° C or –459.67° F. The "size" of a one degree change in temperature is exactly the same in the Celsius and Kelvin scales, so the freezing point of water is at a temperature of 273.15 kelvins (that is, 273.15 degrees above absolute zero). Water boils at a temperature of 100° C, which is 373.15 kelvins (or 212° F).
Notice how we don't say "degrees Kelvin" like we would say "degrees Celsius" or "degrees Fahrenheit". Instead of saying a temperature is "300 degrees Kelvin", we say the temperature is "300 kelvins".
To convert a temperature measurement between the Kelvin scale and the Celsius or Fahrenheit scales, use the following formulas:
|K = C + 273.15
||C = K - 273.15
|K = (F + 459.67) / 1.8
||F = 1.8 K - 459.67
... where K stands for the temperature in kelvins, C for temperature in degrees Celsius, and F for temperature in degrees Fahrenheit.
The Kelvin scale was named after William Thomson, Lord Kelvin, who was a prominent Irish/Scottish physicist and engineer of the latter part of the 19th century. Thomson did important work on the physics of heat as well as other disciplines within the physical sciences.
Shop Windows to the Universe Science Store!
Our online store
includes fun classroom activities
for you and your students. Issues of NESTA's quarterly journal, The Earth Scientist
are also full of classroom activities on different topics in Earth and space science!
You might also be interested in:
Any substance, called matter, can exist as a solid material, liquid, or gas. These three different forms are called states. Matter can change its state when heated. As a solid, matter has a fixed volume...more
Mercury has very little atmosphere. The planet's small size means that its gravity is too weak to hold down a normal atmosphere. There is a very thin atmosphere around the planet. Mercury's thin atmosphere...more
The solar core is made up of an extremely hot and dense gas (in the plasma state). Despite a density of 160,000 Kg/m3, the temperature of 15 million kelvins (27 million degrees Faranheit) prevents the...more
Rising above the Sun's chromosphere , the temperature jumps sharply from a few tens of thousands of kelvins to as much as a few million kelvins in the Sun's outer atmosphere, the solar corona. Understanding...more
The gas in the solar corona is at very high temperatures (typically 1-2 million kelvins in most regions) so it is almost completely in a plasma state (made up of charged particles, mostly protons and electrons)....more
The methane cloud deck of Uranus is found low in the troposphere. The methane clouds are the only clouds to be found on Uranus. The location of the clouds is predicted based upon the temperature at which...more
This is the temperature profile of Uranus' mesosphere. The temperature is the same at all heights until the mesopause, or "top" of the mesosphere is reached. As shown in the figure, the mesopause is placed...more