PaulAstro. The science of spectroscopy indicates that the "fingerprint" of colored lines identifying a specific element in a lab on Earth, is identical to the set of lines obtained through a telescope....with some allowance for red and blue shifting due to Doppler effects and gravitational wells. The relative spacing remains the same.
The distance scale is based upon a number of assumptions of standard candles. You might enjoy the link searching for Cepheids in Northwestern's lab...try:http://www.astro.northwestern.edu/labs/m100/


pete

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A third rate theory forbids.
A second rate theory explains after the fact.
A first rate theory predicts.
A. Lomonosov