Cosmologists believe that the universe has been expanding since the Big Bang. Astronomers observe evidence of this expansion when viewing distant stars through which phenomenon?A) Redshift B) Blueshift C) Gamma pulse D) Background radiation
Biology · Middle School · Thu Feb 04 2021
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Answer: A) Redshift
Redshift is the phenomenon that astronomers observe which provides evidence for the expansion of the universe. When we look at the light coming from distant stars and galaxies, its wavelength is found to be longer than expected. This shift towards the redder part of the spectrum is analogous to the Doppler effect, where the frequency of waves (such as sound) decreases when the source is moving away from an observer. In the context of light from distant galaxies, the increase in wavelength indicates that those galaxies are receding from us, which is considered evidence that the space between galaxies is expanding.