We actually placed the story in April 13291 AD via astronomy. There's a section that shows the night sky clearly and the stars have moved slightly from their cu

We actually placed the story in April 13291 AD via astronomy. There's a section that shows the night sky clearly and the stars have moved slightly from their current positions. Also interestingly enough Antares has gone supernova in the intervening 11278 years. See http://xkcd-time.wikia.com/wiki/Astronomy#The.C2.A013291_Hypothesis http://xkcd-time.wikia.com/wiki/Astronomy#The.C2.A013291_Hyp...