There is a theory called Microwave Background Radiation (CMB) which in short tells us that if we look into space what we are seeing is an image of the past, I mean, the sun is located about 150 million kilometers from Earth by what the sun's rays take 8 minutes to reach us therefore we are seeing an image of the sun 8 minutes ago, in the same way it happens with the star Proxima Centauri which is located more or less 4 light years from us is say we are seeing an image of that star for 4 years ++
