Winter solstice instant of the solstice can be calculated, direct observation of the solstice by amateurs is impossible because the sun moves too slowly or appears to stand still (the meaning of "solstice"). However, by use of astronomical data tracking, the precise timing of its occurrence is now public knowledge. One cannot directly detect the precise instant of the solstice (by definition, one cannot observe that an object has stopped moving until one later observes that it has not moved further from the preceding spot, or that it has moved in the opposite direction). Further, to be precise to a single day,
Julian day given "Julian date" is "October 5, 1582", this means that date in the Julian calendar (which was October 15, 1582, in the Gregorian calendar—the date it was first established). Without an astronomical or historical context, a "Julian date" given as "36" most likely means the 36th day of a given Gregorian year, namely February 5. Other possible meanings of a "Julian date" of "36" include an astronomical Julian Day Number, or the year AD 36 in the Julian calendar, or a duration of 36 astronomical Julian years). This is why the terms "ordinal date" or "day-of-year" are preferred. In contexts