the discovery of a 140 year old supernova reminds me of julian barbour’s remark (can’t recall where i heard it…) concerning so-called “deep” time – the age of the earth, for example. to paraphrase he said that we know how “old” the earth is by studying rocks that exist right now.
this image, btw, is a careful composite of a 1985 radio image (blue), with a 2007 x-ray image (red) of the ‘same’ event/location.
“the past isn’t even past” Faulkner