Of particular note: there is now excellent astronomy software which many geeks already have on their systems, which can be used to nail down dates from constell

Of particular note: there is now excellent astronomy software which many geeks already have on their systems, which can be used to nail down dates from constellations fairly accurately. xkcd fans used Stellarium [0] to determine the epoch (at one point, picking out a specific day and hour due to the locations of Jupiter and Venus [1]!) [0] http://www.stellarium.org/ http://www.stellarium.org/ -- which was forked for use in portable planetariums at http://digitaliseducation.com/products-nightshade.html http://digitaliseducation.com/products-nightshade.html [1] http://xkcd-time.wikia.com/wiki/Astronomy#The.C2.A013291_Hypothesis http://xkcd-time.wikia.com/wiki/Astronomy#The.C2.A013291_Hyp...