In 2021, amateur astronomer Dana Patchick tracked SN 1181 back to its location in the nebula Pa 30 that's situated within the Milky Way, determining the supernova erupted around 1,000 years ago (about 200 years before our ancestors spotted and documented it).
The part in parentheses is the article author's extrapolation, based on a misunderstanding of the research, which is somewhat understandable when coming from members of the general public.
The nebula (and the supernova in 1181) is around 2.3 kpc or 7,500 light-years away, so it exploded about 8,500 years ago. We see the supernova remnant nebula at the same distance our ancestors saw the supernova. "Around 1,000 years" is how long it took the nebula to expand to the size at which we see it now (we can measure its size & expansion velocity, so we can extrapolate backwards).
"Around" expresses uncertainty, which in the original 2021 research paper was on the scale of centuries: 990 +280/-220 (meaning anything between 750 AD and 1250 AD, with probability peaking in 1030) . However, this level of uncertainty is dwarfed by the range of potential observable supernova remnant ages, which can be anything from a few years to a few tens of thousands of years, so this "around 1,000" was already a good match with the actual observed age of 843 years.
However, in fact, newer research already narrowed down the age of the nebula further to 1152 +77/−75 (that is, between 1080 and 1227 with peak probability in 1152), making for an even better match.
Facebook
Twitter
Instagram