[Kevin Fitch]

Kevin Fitch  asked the Naked Scientists:
   
I have heard that observations of electromagnetic spectrum may be used to determine the composition of stars, e.g. this is how helium was discovered.

But, I have also heard that observations of electromagnetic spectrum may be used to determine the temperature of an object. How is it that this single concept can be used to make two very different measurements? Is it ever the case that the temperature of an object may confuse measurements of its composition or vice-versa?
 
Kevin from Glenwood, Maryland, USA

What do you think?