Exam-style question
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What does a redshift in the spectrum of a distant galaxy indicate?.
- A.The galaxy is moving towards us
- B.The galaxy is moving away from us
- C.The galaxy is stationary
- D.The galaxy is rotating
Model answer
What a good answer should say
- The galaxy is moving away from us
Explanation
Why this works
A redshift occurs when the wavelength of light from an object is stretched, indicating that the object is moving away from the observer. This is a key piece of evidence for the expanding universe.
Common mistake
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