Hello. So I always hear people say, "If someone flew in a ship at light speed to a far away star and then came back to earth, and it only took him two years to travel (the star being a light year away). When he came back all of his family/friends would have been dead for a long time." My question is about the people on earth... If instead we change our perspective to those on earth, and they observed the travel of this astronaut to the far-away star with a telescope, wouldn't relativity imply that the people on earth would see the astronaut die in the same way the astronaut would observe his friends? The way I understand relativity is that while to the astronaut it seems that he had not aged more than 2 years, to the earth observers they would see him age dramatically because of his travel at the speed of light? I hope I was clear in my question. I've never heard anyone discuss this thought experiment from the perspective of the earthians.