Exam-style question
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How is redshift used to infer the recession of galaxies?.
- A.By measuring the increase in brightness
- B.By observing the change in wavelength of light
- C.By calculating the distance to the galaxy
- D.By analyzing the temperature of the galaxy
Model answer
What a good answer should say
- By observing the change in wavelength of light
Explanation
Why this works
Redshift is observed as a change in the wavelength of light emitted from a galaxy. A shift towards longer wavelengths indicates that the galaxy is receding, which supports the theory of an expanding universe.
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