Things in space being “xxxx lightyears away”, therefore light from the object would take “xxxx years to reach us on earth”

Question

I don’t really understand it, could someone explain in basic terms?

Are we saying if a star is 120 million lightyears away, light from the star would take 120 million years to reach us? Meaning from the pov of time on earth, the light left the star when the earth was still in its Cretaceous period?

In: 292

Answer 1

In everyday life we use the same convention: NYC is 6 hours flight away from LA. State A is 2 hours drive away from state B.

We basically use time to measure distance. That sounds a bit strange but we actually implicitly agree on the standard speed. That are in the example plane speed, car speed, respectively. So we no longer need to state explicitly speed.

The same applies to light year and light speed.