The era: sometime before A.D. 1200, when Saxo Grammaticus first wrote down the story of Prince Hamlet. It's summer in Elsinore, during the white nights, and the Danes are busy night and day forging weapons and building ships of war. At just before one in the morning, the ghost of King Hamlet appears to the watch on the castle battlements; a few minutes later, as in the ballad of Usher's Well, "the cock doth crow, the day doth show, the channerin worm doth chide," and the ghost returns to Purgatory until nightfall. An interesting paradox that a ghost, restricted to darkness, should first appear when the nights are short. By contrast,
Some say that ever 'gainst that season comes
Wherein our Saviour's birth is celebrated,
This bird of dawning singeth all night long;
And then, they say, no spirit dare stir abroad...
To underline the paradox: around Christmastime and the winter solstice, during the longest nights of the year, ghosts keep to their own haunts.
Like Sophocles in Oedipus the King, Shakespeare often rhymed derangements in the political order--breaks in the lawful succession of kingship--with unnatural episodes in Nature. On the morning of the day after Macbeth murders Duncan, somewhere else in hag-ridden (haggis-ridden?) Scotland, Macduff's cousin Ross mentions in passing that "a falcon towering in her pride of place/ Was by a mousing owl hawk'd at and kill'd." In Hamlet, Horatio, who waits with the watchmen to see the Ghost on the third night of its appearance, refers to harbingers of Caesar's assassination, including "stars with trains of fire and dews of blood,/ Disasters in the sun;*" and lunar eclipses, alluding to similar recent events in Danish skies. Shakespeare intensifies this trope with a stark opposition between truth and appearance: "Meet it is I set it down/ That one may smile and smile and be a villain."
So, at one a.m. on Elsinore's battlements, how bright was it, and what night was it? In The Adventures of Tom Sawyer, Mark Twain tells how Aunt Polly nails Tom for having gone swimming against orders because he had sewn his collar back on afterwards with black thread rather than white; the point was that it was just dark enough not to be able to distinguish between them. Perhaps Shakespeare's contemporaries had some similar criterion for degrees of darkness; in any case, that Horatio could see at one a.m. that the Ghost's beard was "a sable silvered"--black hairs with white ones among them--shows that it must have been near the brightest night of the year.
In Copenhagen, twenty miles south of Helsingor, between early June and early July, "nautical twilight"--the time during which bright stars are still visible and the horizon is just distinguishable from the sky--never gives way to true night. "Civil twilight" in Copenhagen--during which objects on the ground can be clearly distinguished from one another by the sky's ambient light--was expected to begin at 3:24 a.m. Daylight Savings Time (that is, 2:24 a.m.) between 16 and 26 June 2011. Given poetic license, at one o'clock it might have been almost bright enough to read.
I suggest that the Ghost makes its first appearance on the summer solstice, 21 June; that Act I, Scene i of Hamlet takes place two nights later, very early on 23 June; and that Prince Hamlet first sees his father's spirit in the early morning of 24 June, exactly halfway around the year from "that season...wherein our Saviour's birth is celebrated." I first thought of writing this on the summer solstice 2011, last Tuesday. In Cape May Point, New Jersey, at three this morning (26 June 2011) the mockingbirds--the local birds of dawning--began their song.
*Presumably, "disasters in the sun" refers to celestial events (like comets and supernovae) visible in broad daylight; the Crab Nebula, for example, is the remnant of such a supernova, which dominated the daylight sky for some time during the year A.D. 1054. "Disaster" means "bad (unfavorable) star."