One hundred and eighty degrees, and a very visible planet
The opposition is a half circle, 180 degrees of separation, with an eight degree orb. Since the Sun moves about a degree a day and Saturn hardly moves at all against that, the aspect holds for about a fortnight either side of exact.
This occurs once in each Sun to Saturn cycle of roughly 378 days. Astronomically it is the moment Saturn is opposite the Sun as seen from Earth, which means Saturn rises as the Sun sets, is at or near its closest approach, and is at its brightest in the whole cycle. It is also the period during which Saturn appears retrograde, because Earth is overtaking it on the inside track.
So this aspect and the conjunction are exact astronomical opposites in a literal sense. One has Saturn invisible in the glare, the other has it up all night. Whatever you make of the interpretation, that part is checkable.
Identity across the table from obligation
The Sun in the tradition is conscious purpose and the sense of being someone in particular. Saturn is time, structure, restriction and the account that has to be settled. An opposition does not blend them. It sets them in opposing signs and, in most charts, opposing houses, so that each is permanently answerable to the other.
The classic description is external authority. Where the conjunction internalises the limit, the opposition tends to meet it in a person, an institution or a set of circumstances that will not move. Readings often mention a parent, an employer, a rule that arrived at the wrong moment. Whether that is a fair account of anyone's life is a separate question, but it is what the tradition says.
The other standard note is projection. Oppositions are the aspects most often described as showing up in other people first, so the seriousness, caution or heaviness attributed to someone else may belong to the chart holder. Practitioners tend to read progress on this aspect as the point where the two ends stop being a fight and start being a negotiation.
Signs, houses and the retrograde question
Because the two bodies are half a circle apart, they always sit in opposing signs, and the pairing tells you a great deal. Sun in Leo opposite Saturn in Aquarius is the sharpest version by traditional dignity, since each body is in the sign the other rules. Sun in Libra opposite Saturn in Aries is a quieter arrangement with a very different balance of strength.
The house axis names the arena. First and seventh reads as self against partner. Second and eighth reads as resources and what is owed. Fourth and tenth is the family against public life version, and it is the one most often written about.
Saturn is retrograde at almost every exact opposition to the Sun, which is a consequence of the geometry rather than a separate feature of the chart. Some astrologers read a retrograde Saturn as an internalised authority. Others point out that it is nearly universal in this aspect and treat it as carrying no extra information.
Orb, and what to read off your own chart
The eight degree orb is generous, and the difference between one degree and seven is large. Tight oppositions are usually described as unmistakable. Wide ones, particularly out of sign ones where the Sun is at the end of a sign and Saturn at the start of the sign after the opposing one, lose much of the description.
Two further checks are worth making. Look for anything square to both ends, since that makes a T-square and reroutes the whole pattern through the third body. Look also at where the Moon sits, because the Moon's relationship to a Sun to Saturn axis is one of the things practitioners weigh before deciding how heavy a chart really is.
The check above gives you your exact separation, both signs and both houses, which is where the general account either fits or does not.
Questions people ask about this
Was Saturn actually visible at my birth?
Yes, if the opposition was close to exact. At opposition Saturn rises around sunset and sets around sunrise, sits near its closest approach to Earth and is at its brightest for the cycle. Cloud and light pollution aside, it was above the horizon all night.
Why is Saturn usually retrograde in this aspect?
Because outer planets appear to move backwards when Earth overtakes them, and that overtaking happens around opposition. So a natal Sun opposite Saturn very nearly always comes with a retrograde Saturn. It is a consequence of the geometry, not an independent factor.
Is Sun opposite Saturn worse than the square?
Neither is ranked above the other. Both are hard aspects. The square works through friction and tends to force action, while the opposition tends to produce awareness, stalemate or a sense that the difficulty is located in someone else.
What orb applies here?
Eight degrees, so a separation of about 172 to 188 degrees. Given the Sun's daily motion of roughly one degree, that covers about a fortnight either side of the exact opposition.
Does this aspect say something about my father?
Traditional readings connect the Sun and Saturn to paternal authority, and many textbooks say so directly. It is an interpretation rather than a fact about anyone's family, and the house placement, particularly the fourth and tenth axis, does more to shape that part of the reading than the aspect alone.
How often does the Sun oppose Saturn?
Once in every Sun to Saturn cycle of about 378 days, so slightly less often than once a year. The date drifts forward by roughly two weeks each year as Saturn moves through the zodiac.