2007-03-17 05:40:55 · 5 answers · asked by Kevin 1 in Science & Mathematics ➔ Astronomy & Space
They examine the light that comes from the star (its spectrum).
Which is called Spectroscopy
2007-03-17 05:41:58 · answer #1 · answered by spaceprt 5 · 0⤊ 0⤋
The hot gases emit radiation which can be compared to the radiation from known elements that has been studied in the laboratory. The red shift is compensated for while comparing the spectral lines.
2007-03-17 05:45:56 · answer #2 · answered by Swamy 7 · 0⤊ 0⤋
Various different materials emit light, or absorb light, at different wavelengths. And exact wavelengths are fixed by the laws of quantum physics so every element has a 'fingerprint' in its emission and/or absorbtion spectra. By looking at these spectra (the process is called 'spectroscopy') it's actually fairly easy to tell the composition of distant objects.
Doug
2007-03-17 05:57:24 · answer #3 · answered by doug_donaghue 7 · 0⤊ 0⤋
if you take the light from the object and send it through a prism there will be little black bands in it. These bands are the wavelengths of light that the object doesn't reflect.
Each element has it's own band or set of bands, so if you look at whats missing you can compare it to the known elements and determine what they are made of.
2007-03-17 05:46:15 · answer #4 · answered by Justin H 4 · 0⤊ 0⤋
They examine the light from it. Redshift, blueshift, standard stuff. Each element has it own unique signature. Oh, if it's yellow, hydrogen. If it's red, it's helium. When it runs out of helium, run for your life!
2007-03-17 05:55:12 · answer #5 · answered by Anonymous · 0⤊ 0⤋