I am just guessing, but if a galaxy was 10 billion light years away when the light left the galaxy it would appear to be 10 billion light years away, but in an expanding universe that galaxy also moved away from us for 10 billion years. So, appearing 10 billion years away today might mean it’s 30 billion light years away right at this moment in time.
I am just guessing, but if a galaxy was 10 billion light years away when the light left the galaxy it would appear to be 10 billion light years away, but in an expanding universe that galaxy also moved away from us for 10 billion years. So, appearing 10 billion years away today might mean it’s 30 billion light years away right at this moment in time.