in the early 1900s, scientists discovered that certain properties of light were changed depending on the distance between Earth and the object being
observed. In 1929, Edwin Hubble compared this phenomenon to the relative distances between a certain set of stars. Hubble found that when the two sets
of data were graphed against one another, each star appeared to be farther from one another than what the relative distance indicated. With this
information, Hubble concluded the universe is expanding.
What phenomenon was discovered by early astronomers and used by Hubble to confirm that the universe is expanding?
The light emitted by the galaxies becomes brighter as they move away from one another
The light emitted by the galaxies becomes whiter as they move away from one another.
The wavelength of the light emitted by the galaxies shifts to the blue region of the spectrum as the galaxies move away from one another.
The wavelength of the light emitted by the galaxies shifts to the red region of the spectrum as the galaxies move away from one another.