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

You got it: one lightyear is the distance light travels in one year (assuming the light is traveling through a vacuum). So every time we look at an object in space that is multiple lightyears away, we are seeing light that bounced off of/was emitted by that object some number of years ago (e.g. 100 lightyears = the images we receive are 100 years old).