1)  How long it takes for the light from the object to reach us.
2)  The energy of the light.
3)  The position of the light in the sky.
   
                     
   
Wow That's a lot of Energy!!
 
                     

So you are looking at this X-ray image on the right and thinking,"That's really cool!  Wonder what it is though.  I have no idea what I'm looking at."  You are about to discover exactly what you are looking at.

You are about to do a simple experiment with the Chandra software.  Follow the instructions for "Activity 6" when you click on the link below.  When you are done, come back here.

 

             
     

At this point you are probably thinking, "big deal".  However, this is a big deal.  You may not realize it, but you can now find what elements are in any image that Chandra has on file.

This is how you do it.  Click here and follow the instructions.  You can ask Chandra to display areas that have energy spectrum that match a particular element

     
                     
       
You can also click on the periodic table below and use that website to match up an energy spectrum you discovered and its matching element.