A band barely wider than a degree
The figure worth having for a birthday is not the sign but the longitude. On this date the noon Sun has stayed inside a band a little over a degree wide for more than a century, running from about four and a third to about five and two thirds degrees of Sagittarius.
That stability surprises people, because the year and the calendar are visibly not the same length. A tropical year is close to three hundred and sixty five and a quarter days, so if nothing corrected for it, dates and seasons would separate at a rate of about a day every four years and the sign for this birthday would have changed several times over.
The leap day is the correction, and it is a good one. The Sun slips about six hours later against the calendar each ordinary year, then jumps back almost a full day when February gains its extra date. The net effect over the cycle is close to nothing.
Where the leftover goes
The cancellation is not perfect. A tropical year is slightly under three hundred and sixty five and a quarter days, so adding a leap day every four years slightly overcorrects. The Gregorian rule handles this by skipping the leap day in century years that are not divisible by four hundred, which is why 1900 was a common year and 2000 was not.
What survives all that is a drift of roughly a day per century in the same direction, which is why the low end of the band belongs to the later years in the record and the high end to the earlier ones. It is a real effect, and at this size it is far too small to move the sign.
None of this is astrology. It is calendar arithmetic, and it is the reason a printed date range for a sign is nearly right and never exactly right.
The face this degree lands in
Five degrees sits in the first decan of Sagittarius, the opening ten degrees of the sign. Decans are the ten degree divisions that every sign carries, thirty six of them around the zodiac, and they descend from Egyptian star lists that marked out the hours of the night.
Two schemes assign rulers to them and they disagree here. The Chaldean order, cycling Mars, Sun, Venus, Mercury, Moon, Saturn and Jupiter from the start of Aries, delivers Mercury to this face. The triplicity scheme starts each sign's decans from itself, so the first face of Sagittarius stays with Sagittarius and with Jupiter.
The tradition reads the Jupiter version as the sign at full strength and the Mercury version as that same outlook made to argue in specifics. Which one a given writer means is often left unsaid, and that is worth knowing before comparing descriptions.
What is still open
Fixing the solar degree settles the Sun and nothing else. The Moon travels about thirteen degrees a day, so on any single date it can occupy either of two adjacent signs and the hour of birth decides. The Ascendant runs through the entire zodiac in a day, changing by roughly a degree every four minutes.
That is the honest limit of a birthday page. A date and a place will give you the Sun with confidence, an approximate Moon, and no Ascendant at all. Everything that makes a chart individual sits in the placements a date cannot reach.
The widget above takes your year and birthplace, computes the solar longitude for that moment rather than reading it off a table, and tells you how far the position sits from the nearest sign boundary. On this date the answer will be comfortable, which is itself useful to have confirmed.
Questions people ask about this
Is 27 November always Sagittarius?
Yes, in every year in the record from 1930 to 2035 and at any hour of the day. The Sun is around five degrees into the sign, which is far too deep for the calendar drift to reach the boundary.
How precise is the degree figure?
The band quoted is measured at noon, so a birth in the early morning or late evening sits up to half a degree either side of it. The widget above uses your actual hour and place instead.
Why do some sites give a different degree?
Usually because they quote noon in a single year, or a single time zone, without saying which. A degree stated without a year and a location is incomplete rather than wrong.
What decan does this birthday fall in?
The first decan of Sagittarius. Its ruler is Mercury under the Chaldean order and Jupiter under the triplicity scheme, and reputable sources use both.
Does a low degree mean a weak Sagittarius?
No. A Sun at five degrees of a sign is as much in that sign as a Sun at twenty five. Degree affects aspects and house position, not sign membership.
What would change my reading most?
Your birth time, because it fixes the Ascendant and the house each planet occupies. Those are the layers that differ between two people who share this birthday.