You might be able to tell the year from astronomical observations, assuming you still know some facts like the dates of earlier eclipses, conjunctions, .... Onc

You might be able to tell the year from astronomical observations, assuming you still know some facts like the dates of earlier eclipses, conjunctions, .... Once you know the year, month and day you could calculate the day of the week using the doomsday rule. https://en.wikipedia.org/wiki/Doomsday_rule https://en.wikipedia.org/wiki/Doomsday_rule