The temperature at the surface of the Sun (top) is about 6,000 kelvins. The Sun's atmosphere is much hotter. The bottom image shows ultraviolet "light" coming from the Sun's atmosphere. The temperature in that part of the Sun's atmosphere is around 70,000 kelvins.
Click on image for full size
Images courtesy of SOHO (ESA & NASA).
Kelvin Temperature Scale Used in Astronomy
The Kelvin scale is a temperature scale that is used a lot in astronomy. You probably know about the Celsius (or Centigrade) scale, which is part of the metric system of measures. If you live in the USA, you also know about the Fahrenheit scale, which is used in the English system of measures.
Why do astronomers need another temperature scale? On Earth, the temperatures we feel most often are pretty much where water is liquid. A temperature scale that has "reasonable" numbers for "normal" temperatures makes sense for day-to-day use on Earth. For example, Earth's average temperature is around 15° C (49° F). Fifteen and 49 are pretty easy numbers to deal with. It wouldn't be so good if our temperature scale used really big numbers (like 6,437°) or really small numbers (like 0.052°) or negative numbers (like -147°) for normal temperatures. The Celsius and Fahrenheit scales are set up to have "reasonable" numbers for common temperatures on Earth.
Temperatures in space are often much colder or much hotter than we are used to on Earth. Comets and icy moons have temperatures close to absolute zero. Stars can have temperatures of thousands of degrees or higher. The Kelvin temperature scale is good to use for really hot and cold places in space. There aren't any negative numbers in the Kelvin scale. That makes it good to use for really cold temperatures. The temperature on Saturn's icy moon Triton is around 38 kelvins (that's -235° C or -391° F).
One degree in the Kelvin scale is "bigger" than a degree on the Fahrenheit scale. That means we can use smaller numbers for really hot things if we use the Kelvin scale. The core of the Sun has a temperature around 15 million kelvins, which is the same as 27 million degrees Fahrenheit. The Kelvin scale is good to use for both really cold and really hot things and places. That's why astronomers and space scientists use it a lot. Other kinds of scientists sometimes use the Kelvin scale too.
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:
What types of instructional experiences help K-8 students learn science with understanding? What do science educators teachers, teacher leaders, science specialists, professional development staff, curriculum designers, school administrators need to know to create and support such experiences?...more
Liquid is one of the four common states of matter. The three others are gas, solid, and plasma. There are also some other exotic states of matter that have been discovered in recent years. A liquid does...more
Not long ago, many people thought that comets were a sign that something bad was about to happen to them. People didn't understand how objects in the sky moved, so the sight of a comet must have been...more
Triton is the largest moon of Neptune. It is a very unusual moon. The poles of Triton are especially interesting. Triton has a polar ice cap at the South Pole. Earth, of course, has ice caps at its poles...more
The butterfly effect refers to how small things can have big consequences. As an example, consider two different computer simulations of the path of a hurricane. Both of them start from some initial state,...more
The Kelvin scale is a temperature scale that is used a lot in astronomy. You probably know about the Celsius (or Centigrade) scale, which is part of the metric system of measures. If you live in the USA,...more
Infrared (IR) radiation is a type of electromagnetic radiation. Infrared "light" has a longer wavelength than visible light. Red light has a longer wavelength than other colors of light, and infrared has...more
Magnetism is one of the main forces of nature, like the force of gravity. Like gravity, which causes objects to be attracted to each other, magnetism causes magnetized objects to be attracted to each other....more