This is called red-shift. Light is shifted towards the long wavelength, red end of the spectrum. This tells us that: other galaxies are moving away from our galaxy; the Universe is expanding.

A tiny red speck, spotted by the ... understand what happened just after the Big Bang. The age of these very early galaxies is inferred by their "red shift", which is measured using a technique ...

This is called red-shift. Light is shifted towards the long wavelength, red end of the spectrum. This tells us that: other galaxies are moving away from our galaxy; the Universe is expanding.