The figure first
At noon in each year from 1930 to 2035, the Sun on 14 April stood between roughly twenty three and a half and twenty five degrees of Aries. Call it twenty four. That is not an average hiding a wide scatter, it is the whole range.
Compare that with the way birthdays are normally described. A date range tells you the sign and nothing else, and it changes by a day or so between sources. The degree is stable to well under two degrees over four generations, and it is the more specific of the two facts.
Why the drift cancels
The Earth takes about three hundred and sixty five and a quarter days to go round the Sun. A common calendar year is a quarter of a day short, so each year the Sun reaches a given longitude about six hours later by the clock than it did the year before. Left alone, that would walk the date through the sign.
February then gains a day every fourth year, which shifts everything back by about eighteen hours in one step. Over the four year cycle the six hour creep and the one day correction very nearly cancel. What is left is a small residual wobble, and the century rule that skips a leap day in 1900 and 2100 keeps even that from accumulating.
What the steady figure buys you
Twenty four degrees of Aries lands in the third face of the sign, the ten degree band from twenty to thirty. That band is given to Venus in the Chaldean order and to Jupiter in the triplicity scheme, so a source quoting a face ruler for this birthday has quietly picked a side.
The band is also the layer that tells one Aries birthday from another. Two people can both be Aries and share almost nothing in the older material if one was born in the first face and the other here in the last. Sign alone flattens that distinction, and it is exactly the distinction a stable degree lets you make.
It is worth saying what the stability is not. It does not mean the Sun is in the same place at the same clock time each year, only that the longitude on this calendar date stays within a narrow band. Within a single 14 April the Sun still moves about a degree from midnight to midnight, which is why a birth early in the morning and one late at night differ slightly even in the same year.
Where the stability stops
Nothing else in a chart behaves this way. The Moon moves through the zodiac in under a month, so on the same date in different years it can be almost anywhere, and even within one 14 April it can be in either of two signs depending on the hour. The rising sign turns through all twelve in a day.
So the date fixes the Sun and leaves the rest wide open. That is not a small point. It is the reason a birthday alone cannot describe a chart, and the reason the widget above asks for the hour and the birthplace before it reports your exact degree and your margin from the nearest boundary.
Questions people ask about this
What sign is 14 April?
Aries, in every year checked at noon from 1930 to 2035. The change into Taurus is still several days off, so no year in the sample comes near the boundary.
Why does the degree hardly change?
Because the calendar and the orbit stay in step. The Sun arrives about six hours later each common year, and the extra day in a leap February pulls it back, so the two effects cancel over the cycle.
How exact is the twenty four degree figure?
The full range at noon over that century is about twenty three and a half to twenty five degrees. Your own figure depends on your year, your hour and where you were born, which is what the widget above uses.
Which decan is this?
The third decan of Aries, twenty to thirty degrees. The Chaldean order gives it to Venus and the triplicity scheme gives it to Jupiter.
Does the stable degree mean my chart is predictable?
No. It means one placement out of many is fixed by the date. The Moon, the ascendant and the houses all depend on details the calendar does not carry.
Is 14 April ever Taurus?
Not at any point in the sampled century. The Sun does not reach the Taurus boundary until around 20 April, and even then the exact moment moves by up to a day and a half.