[ETL]

Blueshift vs Redshift.

As with the changing pitch of a moving car's horn, light waves can shift toward higher or lower frequencies. Higher frequency = shorter wavelengths (blueshift). Lower frequency = longer wavelengths (redshift). Blue = approaching. Red = receding.

[Garth Tater]

The author says:
the longer the light has traveled to reach us, and the more stretching it has accumulated.

This doesn't make sense to me. The red shift occurs at the moment the light left the object - what is stretching it out after that time?