What is the best way to determine a galaxy's redshift?
A)Find the galaxy's apparent distance,and look up the redshift based on Hubble's law.
B)Find the color of the galaxy,and estimate its distance based on how red the galaxy is.
C)Take a spectrum of the galaxy,and measure the difference in wavelength of spectral lines from the wavelengths of those same lines as measured in the laboratory.
D)Measure the magnitude of the galaxy,estimate its distance,and calculate its redshift using Hubble's law.

Question

Quizplus · Accepted Answer

The most accurate way to determine a galaxy's redshift is to take a spectrum of the galaxy and measure the difference in wavelength of spectral lines from the wavelengths of those same lines as measured in the laboratory. This method is called spectroscopic redshift and is the most reliable way to determine a galaxy's redshift. Option A and D involve estimating the distance of the galaxy, which can introduce errors. Option B is not a reliable method as the color of a galaxy can be affected by various factors, such as dust and age, and does not necessarily correspond to its distance or redshift.

What Is the Best Way to Determine a Galaxy's Redshift