"is 160,000 light years away in the constellation Dorado.... The supernova occurred about 400 years ago"
So if it is 160,000 light years away, doesn't it mean it would take that long for the light to reach the Hubble telescope? So how could it have occurred 400 years ago and the light reach us in that time?
I think I finally figured this out. The way this is written is not exactly clear. While SNR-0509 is 160,000 light years away, the light reached earth about 400 years ago. Therefore the statement would read better if written as
"is 160,000 light years away in the constellation Dorado.... The supernova occurred about 160,400 years ago"
- The problem is that you're assuming absolute time. This is one of the less intuitive consequences of relativity; you may want to read our article on relativity of simultaneity to learn more. I know what it feels like, wanting to say "if (location) is X light-years away from us, and we detected the light from (event at location) Y years ago, then (event) really happened (X+Y) years ago, not Y years ago". But it really doesn't work that way. From the stellar remnant's frame of reference, the supernova was 160400 years ago. From our frame of reference, the supernova was 400 years ago. And these are both true at -- pardon the expression -- the same time. DS (talk) 14:28, 6 September 2012 (UTC)
I think it would be simpler to say that "The light from the supernova began reaching Earth about 400 years ago," — Preceding unsigned comment added by Jamarsac (talk • contribs) 17:45, 6 May 2015 (UTC)