The measured position
Taken at noon in every year from 1930 to 2035, the Sun on 19 May has stood between about twenty seven point six and twenty nine degrees of Taurus. The Sun covers a little under one degree a day at this time of year, so the crossing into Gemini follows within a day or two, generally on the twentieth or twenty first.
Even at the top of that range the sign is not in doubt. Twenty nine degrees of Taurus is inside Taurus. The distance to the boundary is small in degrees but it is more than a day in time, and no plausible birth hour on this date crosses it.
The narrowness of that range is the leap year cycle at work. A tropical year runs a little over three hundred and sixty five days, so the Sun reaches a given point about six hours later each calendar year until February gains a day and pulls the reckoning back. The position on a fixed date therefore repeats within a small band rather than drifting away over the decades.
What the tradition says about final degrees
Some older material treats the twenty ninth degree of any sign as a distinct case, sometimes called the anaretic degree, and reads a planet there as being at the end of a process and about to change condition. Modern practice varies widely on how much weight to give it, and plenty of practitioners give it none.
What is worth noting is that this is a reading about position within a sign, not a claim about fortune. Nothing here is treated as good or bad luck. If your calculated degree comes back below twenty nine, which it will in most years, the question does not arise at all.
The decan and its rulers
Anywhere past twenty degrees of Taurus belongs to the third decan. The Chaldean order gives it to Saturn, dealing the visible planets around the zodiac in order of apparent speed. The triplicity scheme assigns Taurus, Virgo and Capricorn to the three bands and so also lands on Saturn for the last.
Above that sits the sign ruler, Venus, and the sign itself is fixed earth. The tradition reads the combination as an attachment to the tangible under a good deal of restraint. Read it as tradition; it is a description handed down, not something the position proves.
Reporting both schemes is the practice here. They agree on this band, which is convenient, but in other parts of the zodiac they differ, and presenting either as the single correct answer would misdescribe what a decan ruler is. It is an assignment made by a tradition, and the tradition has more than one version.
The date still leaves most of the chart open
The precision of the solar degree can be misleading. Knowing the Sun to a fraction of a degree tells you nothing about the Moon, which moves about thirteen degrees a day and can be in either of two signs across a single 19 May, or about the rising sign, which cycles through all twelve in twenty four hours.
The widget above will give you your own solar degree from your year, hour and birthplace, and will report exactly how far that fell from the Gemini boundary. For anything beyond the Sun, a birth time is the piece that has to be found.
Questions people ask about this
Is 19 May the last day of Taurus?
Usually not quite. The Sun typically crosses into Gemini on the twentieth or twenty first, so 19 May sits a day or so short of the end in every year sampled.
What degree is a 19 May Sun?
Around twenty eight of Taurus, with the range across 1930 to 2035 running from about twenty seven point six to twenty nine at noon. Your hour and birthplace shift it slightly.
What is the anaretic degree?
It is a name some older material gives the twenty ninth degree of any sign, read as a placement at the end of its condition. Opinion on its importance is divided and it is not treated here as fortunate or unfortunate.
Am I a Gemini if I was born late in the day?
No. The boundary is more than a day away on this date, and a birth hour can only move the Sun by a fraction of a degree, so the sign holds across the whole of 19 May.
Which decan applies?
The third decan of Taurus, from twenty to thirty degrees, ruled by Saturn in both schemes in common use. The tradition reads it as the most reserved section of the sign.
Does being near the end of a sign matter for aspects?
Yes, and that is the practical use of a degree. Aspects are measured in degrees, so a late Taurus Sun contacts different placements from an early one, whatever the sign label says.