The degree behind the date
Sagittarius begins when the Sun reaches two hundred and forty degrees of ecliptic longitude, in the third week of November. By 8 December the Sun has covered roughly half the sign. Taking noon as the reference point, births on this date since 1930 fall between fifteen and a half and just under seventeen degrees.
That figure is the part almost no birthday page prints, and it is the only piece of a solar position carrying any detail. A sign is a thirty degree band, so naming the sign alone locates the Sun to within a month of movement. Naming the degree locates it to within a day.
It matters for working reasons rather than symbolic ones. Aspects between planets are measured in degrees, house cusps fall at degrees, and a transit either reaches your Sun or misses it by a margin only the degree can show.
Why a century of births lands in the same place
The year to year spread is small. The tropical year runs about six hours longer than a calendar of three hundred and sixty five days, so the noon position on any fixed date creeps forward through a four year cycle and then drops back when February takes an extra day. The result is a saw pattern that never wanders far.
Across the whole span from 1930 to 2035 the noon figure for this date moves by only a little over one degree. The slow drift of the calendar against the seasons is real, but it works at the scale of centuries, and the Gregorian leap rule exists to hold it in check.
So a grandparent born on 8 December and a grandchild born on it have the Sun in nearly the same spot. Their charts differ enormously, though not for this reason.
The middle face and its older ruler
Inside every sign are three bands of ten degrees, called decans or faces. A Sun at sixteen degrees of Sagittarius sits in the second of them, running from ten to twenty. In the Chaldean order, which cycles Mars, Sun, Venus, Mercury, Moon, Saturn, Jupiter from the start of Aries, that band belongs to the Moon.
Jupiter still rules the sign itself. The face ruler is a second layer laid over the first, and the traditional reading of a Jupiter sign under a Moon face is Sagittarius turned inward, with the same appetite for distance and meaning but more of it happening privately.
The triplicity scheme hands the same band to Aries, the next fire sign in order, and reads it as the more restless stretch. Both readings are interpretation, and they are marked as interpretation here.
What the date does not settle
One placement is fixed by the date. The Moon travels between twelve and fifteen degrees a day, close to half a sign, so a birth at breakfast and a birth at bedtime on this date can put the Moon in different signs. Without an hour, the lunar sign here is a choice between two possibilities and occasionally three.
The horizon is worse. The whole zodiac rises in the course of a day, so the Ascendant could be any of the twelve and it shifts noticeably every few minutes. The houses hang off it, which means the area of life each planet is read into moves with it.
On that arithmetic the Sun is the least personal thing in a chart rather than the most. The widget above takes your year, hour and birthplace and returns the exact solar degree together with the distance to the nearest sign boundary.
Questions people ask about this
What sign is 8 December?
Sagittarius, without qualification. The Sun leaves Sagittarius around 21 December, so this date sits comfortably inside the sign in every year and no boundary question arises.
What degree of Sagittarius is 8 December?
Around sixteen degrees at noon, ranging from about fifteen and a half to just under seventeen depending on the year. The widget above gives your own figure from your birth details.
Which decan is an 8 December birthday?
The second decan of Sagittarius, the band from ten to twenty degrees. Its Chaldean ruler is the Moon, while the triplicity scheme assigns it to Aries.
Does the exact degree change anything?
It changes which transits and aspects touch your Sun and by how much. It does not change the sign, and traditional readings of character are attached to sign and decan rather than to a single degree.
Can my Moon sign be worked out from the date alone?
Not reliably. The Moon can cross a sign boundary at any hour, so a date without a time leaves two candidates and sometimes three. A birth time removes the ambiguity.
Why do other pages for this date all read the same?
Because most are written from the sign alone, and everyone born between late November and late December shares that. Anything more specific requires a calculated position rather than a date range.