A boundary you have probably never heard of
Every sign divides into three parts of ten degrees, called decans or faces, and each carries its own ruler. The scheme is older than much of what surrounds it, and it is the layer that separates one Scorpio birthday from another. Popular writing skips it almost entirely, which is why nobody born on this date has been told that it matters here.
Taken at noon from 1930 to 2035, the Sun on 12 November has fallen between about nineteen and twenty and a half degrees of Scorpio. The line between the second band and the third sits at twenty degrees, inside that spread. In earlier years of the span the position tends to land just short of it and in later ones just past, so the honest answer is that it depends on your year.
Why the year decides and the date cannot
The calendar and the orbit do not divide evenly. A tropical year runs about a quarter of a day longer than a common year, so each 12 November arrives slightly earlier against the Sun's actual progress than the last one, and the position creeps backwards. Every fourth February adds a day and hands the drift back.
The result is a small sawtooth rather than a straight line. The Sun's position on this date rocks back and forth across a window under two degrees wide, and because the band boundary sits inside that window, the answer alternates. A year immediately after a leap year gives the lowest figure of the cycle and the year before the next leap day gives the highest.
What the two answers would mean
The second band of Scorpio goes to the Sun in the Chaldean order, and the third goes to Venus. Both sit inside a sign that the older scheme gives to Mars and the modern one to Pluto, so the question is which second influence colours it.
The tradition reads the solar band as Scorpio made visible and the Venusian band as Scorpio attached to something or someone in particular, with attachment carrying the same intensity the sign carries elsewhere. Those are inherited conventions rather than findings, and the difference between them is modest. Knowing which applies is worth a minute; it is not worth an argument.
It is also worth saying what neither band does. Neither one makes a Scorpio more or less of a Scorpio, and neither is the stronger placement. The bands are a subdivision, useful for describing a position precisely, and a second order refinement rather than a foundation of the chart.
Settling it, and what stays open afterwards
The widget above computes the solar position from your own year, hour and birthplace, so it returns a single degree rather than a century-wide window and names the band that goes with it. That is the whole of the ambiguity this date carries.
Everything else a chart contains is untouched by it. The Moon covers around half a sign in a day and may be in either of two signs on this date depending on the hour. The rising sign runs through the full twelve in twenty four hours and depends on latitude as well as clock time. Neither can be read off a birthday, and both say more about a chart than the band question does.
If you were told a decan elsewhere without being asked for your year, treat the answer as a guess. A printed table has to pick one band for the whole date, and on this particular date that choice is wrong for roughly half of the years in the span.
Questions people ask about this
Which decan is 12 November?
The second or the third band of Scorpio, depending on the birth year. The twenty degree boundary falls inside the range this date has occupied since 1930, so the answer alternates through the leap year cycle.
Is 12 November ever a sign other than Scorpio?
No. The Sun is around two thirds of the way through the sign, well clear of both boundaries in every year, so the sign itself is settled.
How do I find out which band applies to me?
Give the widget above your birth year, time and place. It computes the solar degree directly and reports the band, rather than working from a printed range.
Who rules the two bands?
The Chaldean order gives the second band of Scorpio to the Sun and the third to Venus. Both sit inside a sign ruled by Mars in the older scheme and Pluto in the modern one.
Does landing near a band edge weaken the reading?
Not technically. A position at twenty degrees exactly is as much inside its band as one at twenty five. The edge only matters because it decides which band to name.
Does this affect my Moon or rising sign?
No. Those are separate placements with their own degrees, and neither can be worked out from a calendar date. Both need a birth time, and the rising sign needs a birthplace too.