Suppose an absorption line in a spectrum of light from a very distant galaxy is 6000 Angstroms. But the same line in a laboratory on Earth is 4900 Angstroms. What is the distance to the galaxy in parsecs? What is the distance in light years? Show the math and explain what physical characteristic of light is being used to make the distance calculation possible. Why are the different Angstrom measurements being compared? What is happening in the universe to make the math work in determining great distances? Hint: fire engine example in the short video for C10.

Equations:

z = v = d = Plug in the numbers =

Distance in megaparsecs = Distance in light years =

Explanation: