Where the Sun actually stands
Across every year from 1930 to 2035, measured at noon, the Sun on 11 May has occupied between roughly nineteen point nine and twenty one point three degrees of Taurus. The great majority of those years put it past twenty degrees. A few of the earliest, before the drift and the leap corrections had moved on, left it a fraction short.
Twenty degrees is where the second decan of Taurus ends and the third begins. So this date is best described as the opening of the final band rather than as a date that could go either way, though the honest version admits the edge cases at the early end of the range.
The Saturn band in Taurus
Decans are the ten degree divisions inside each sign, and there is more than one scheme for ruling them. The Chaldean order hands the last ten degrees of Taurus to Saturn. The triplicity scheme, which walks the signs of the same element in order, arrives at Capricorn for this band and so also arrives at Saturn. The two schemes disagree in plenty of places, and here they agree.
What the tradition attaches to that band is restraint and endurance placed on top of a Venus ruled sign. Taurus already reads as slow to move; the Saturn third is read as the part of the sign least inclined to move at all, and as the part most concerned with what will still be standing later. That is a reading handed down in the literature, not a measurement.
It is also worth saying what a decan is not. It does not override the sign, it does not make you a partial Capricorn, and it does not divide Taurus into three separate characters. It is a subdivision that the older material used to distinguish parts of a sign, and it is reported here as one, with the ruler named and the scheme it came from stated.
Why the position holds steady
People sometimes assume their solar degree drifts noticeably over a lifetime, or that someone born in 1940 had a very different position from someone born in 2020. Neither is true for a fixed calendar date. The spread on 11 May is about one and a half degrees across a hundred and six years.
The mechanism is the leap year rule. A year is slightly longer than three hundred and sixty five days, so the Sun arrives at a given point a little later each calendar year; the extra day every fourth February resets the accumulated lag. The result is a sawtooth that stays within a narrow band instead of a slide that keeps going.
The parts the date says nothing about
A Sun near twenty degrees of Taurus is one placement. The Moon covers about thirteen degrees a day, which over a single date means it can end in a different sign from the one it started in, so an 11 May birth leaves at least two Moon signs in play until an hour is supplied.
The rising sign is entirely a matter of the clock and the place, since the whole zodiac passes the horizon in a day. Anyone telling you what an 11 May birth means without asking for the hour is describing a Sun sign and calling it a person. The Sun is the least personal placement in a chart, because it is shared by everyone born in the same month.
House placements follow from the rising sign, so they are unknown until the hour is known too. That means the areas of life the tradition assigns to each planet, which is most of the practical content of a chart reading, are also unavailable from a date. The Sun is where a chart starts rather than where it finishes.
Questions people ask about this
Is an 11 May birthday Taurus or Gemini?
Taurus, without qualification. The Sun does not reach Gemini until around 21 May, so this date sits about ten days clear of the boundary in every year sampled.
Which decan does 11 May fall in?
The third decan of Taurus in most years, since the Sun sits just past twenty degrees. In a few years at the early end of the range it stops a fraction short and stays in the second decan.
Who rules the last decan of Taurus?
Saturn, in both of the schemes in common use. The Chaldean order assigns it directly and the triplicity scheme reaches Capricorn for that band, which gives the same ruler.
Does Saturn ruling my decan mean anything difficult?
The tradition reads it as restraint and durability rather than as anything good or bad. A different scheme or a different chart context would shift the emphasis, which is why it is treated as interpretation.
How precisely can my degree be worked out?
To a fraction of a degree, given the date, the hour and the birthplace. The widget above does that and also reports how far you were born from the nearest sign boundary.
Is my birth time needed at all here?
Not for the sign. It matters for the decan only in the borderline years, and it matters a great deal for the Moon, the rising sign and the houses.