The Universe

Evolution of the Universe

How did Edwin Hubble measure galaxies to compute the expansion rate of the universe?

Hubble measured the galaxies’ Doppler effect—the shift in the observed color of objects moving toward or away from an observer—by mounting a machine called a spectrograph on a telescope. He split the light from distant galaxies into its component parts and measured how far the wavelengths of emitted light shifted toward longer wavelengths.


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