: Did anyone ever figure out if there's a known nova or supernova that occurred
: c. 3189 BC? Since we don't know how far away it was, the light might not
: have reached Earth yet.
The sensical approach:
The distance of the observable universe is (without any crazy Einsteinian quirks) is the distance light has had the time to travel from point A to point B. So, if we take the amount of time elasped between the current year and the year of the nova event, we will have the time window light has. Strangely enough, modern science has a pretty convenient unit for figuring out just how far that is: the light year. :)
∴ if we were to take the time of, say, 2811 AD (the beginning of M2, dunno where your particular timeline takes place), then 2811 - (-3189) = 2811 + 3189 = 6000 [woah...was that on purpose?] years. At this particular point in time, we can see at this very moment the events of 3189 B.C. from 6000 l.y. away.
Better?