# How to measure extremely high and low temperatures?

1. Jul 8, 2007

### kwon1jw

I understand that the range of extreme temperature is from 0-15million K. What are the ways that we can measure this? How did they figure out the temperature of the sun?

thermocouple thermometer? blackbody radiation? optical pyrometer? I've tried searching for general information on these online but they usually take me to pages that sell thermometers and pyrometers.

I just registered because I'm taking an introductory online physics course where I have to teach myself basically. This looks like a great site which I will be reading very often to help myself get through physics. I'm pretty intimidated by this subject (and this forum!) because I have never taken a physics class and I'm having some issues already so any help would be greatly appreciated.

Thanks

2. Jul 8, 2007

### Dick

One way to measure the temperature of the sun is to simply model it as a blackbody and determine it by the color - which wavelength is most of the emission in. Another way is the famous exercise of Lifschitz (I think) who challenged a student to estimate the temperature of the sun with a meter stick and thermometer (and a knowledge of thermodynamics). Can you guess what that might have involved?

3. Jul 8, 2007

### Mindscrape

Yes, blackbody can work. Generally, it becomes an issue of statistical mechanics and thermodynamics, but it will really depend on just how low and just how high of temperatures you are thinking of. Is there a specific question you have?

4. Oct 16, 2007

### nuthinmuch

hello fellow members i just need to know a site on which i can find a picture and description of thermometers that go below -80 degrees and above 2000 degrees or you can tell me the description here b ut i really need this for my course work and it would be good if you could help out