What a date range actually is
The Sun enters Scorpio at two hundred and ten degrees of ecliptic longitude, and that moment lands somewhere across 22, 23 or 24 October depending on the year. It drifts about six hours later each common year and jumps back close to a day whenever February gains a date. A published range flattens all of that into a single printed day, which is why one source says the sign begins on 23 October and another says 24.
For this date the rounding does not matter, since 27 October is several days clear of the boundary in every year. But the same tables are used for the boundary dates, where the rounding is the difference between a right answer and a wrong one.
The figure a range cannot carry
At noon in each year from 1930 to 2035, the Sun on this date stood between roughly three and four and a half degrees of Scorpio. That band is narrower than the disagreement between published date ranges, and it says where in the sign the position falls rather than merely that it falls inside.
The stability has a plain cause. The quarter day shortfall in a common year pushes the Sun's arrival about six hours later each time round, and the leap day pulls it back by nearly a full day every fourth February. Over the cycle the two nearly cancel, and the century rule that skips the leap day in 1900 and 2100 stops the small remainder from accumulating.
What the degree unlocks
Below ten degrees the position sits in the opening face of Scorpio. The Chaldean order gives that band to Mars, while the triplicity scheme assigns it to Scorpio itself, which routes it to whichever ruler you take for the sign, Mars in the traditional account or Pluto in the modern one.
The face is the layer that separates one Scorpio birthday from another, and no date range can reach it. Two people born a fortnight apart are both Scorpio and sit in different faces with different attributions in the older material. The degree also determines which aspects the Sun makes to other planets in the chart, which is a further thing a sign label cannot supply.
Aspects are measured in degrees of separation, so a difference of a few degrees decides whether the Sun is in a close relationship with another body or in none at all. Working from a sign alone loses that entirely, since a sign spans thirty degrees and an aspect is usually allowed only a few. This is the clearest case where a range is not a coarse version of a position but a different kind of statement.
The limits of any birthday
Whatever precision is available for the Sun, it does not extend. The Moon crosses the zodiac in under a month, so a fixed calendar date carries no information about it, and within one 27 October it can pass from one sign into the next. The ascendant works through all twelve signs each day and depends on the latitude of birth as well as the hour.
That makes the sun sign the least distinguishing element of a chart, since it is shared with everyone born in the same stretch of any year. The widget above takes the year, the hour and the birthplace, returns the exact solar degree, and reports the distance from that position to the nearest sign boundary.
Questions people ask about this
What sign is 27 October?
Scorpio, in every year checked at noon between 1930 and 2035. The Sun crossed the boundary around 23 October in all of them, so this date carries several days of margin.
Why do published Scorpio dates disagree?
Because the ingress moves by up to a day and a half between years and a printed range has to round it to one day. Different sources round differently, which produces the disagreement.
What degree of Scorpio is this birthday?
Between about three and four and a half degrees at noon over that century. The exact figure depends on your year, your birth hour and your birthplace.
Which decan is 27 October?
The first decan of Scorpio, the band from zero to ten degrees. Chaldean attribution gives it to Mars and the triplicity scheme assigns it to Scorpio itself.
Is the degree more useful than the sign?
It is more specific. It identifies the face within the sign and determines the aspects the Sun makes, neither of which a sign label alone can give you.
Does my birth hour change the answer here?
It changes the degree by up to about one, which can matter for aspects. It cannot change the sign on this date, because the boundary is days away.