Where the Sun is
Noon in every year from 1930 to 2035 puts the Sun on this date between roughly three and a half and five degrees of Leo. The Cancer boundary lies about four days back, so no hour of birth and no time zone reopens the question of the sign. The face changes at ten degrees, still several days ahead.
The position stays inside a band about a degree and a half wide because the six hour annual drift is cancelled by the leap day every fourth year. That is why a calendar date can pin a solar degree at all, which it could not do under a calendar that had been left to slide. Before the Gregorian correction the drift had pushed the seasons well out of step, and dates in that older calendar carry no reliable solar degree at all.
What fixed means
Every sign carries one of three modes, cardinal, fixed and mutable, which repeat in order around the circle. Cardinal signs open the seasons, fixed signs sit in the middle of them and mutable signs close them. Leo is the fixed sign of summer in the northern hemisphere, which is the whole of what the label originally recorded.
The interpretive reading attached to it, persistence and resistance to being redirected, follows from that seasonal position rather than preceding it. The classification is structural and checkable. What the tradition reads into the classification is convention, and it is worth keeping the two apart when almost every source runs them together.
What fire means, and who rules it
Element is the other classification, and it repeats every fourth sign, so the fire signs are Aries, Leo and Sagittarius. Signs of the same element sit at a hundred and twenty degrees from each other, which is the geometry that makes the trine aspect a relationship between signs and not just between planets. The element is a positional fact before it is a temperament.
Leo's ruler is the Sun, one of only two signs whose ruler is a light. That gives a Leo Sun the arrangement traditional writers call domicile, a planet placed in the sign it governs. Its reading is one of unhindered expression rather than of luck, and that distinction is not decoration. Nothing here predicts an outcome. Domicile is a statement about the fit between a planet and the sign it occupies, and it applies equally to everyone born across the whole of the sign.
What none of it reaches
Mode, element, ruler and degree are all properties of one placement. They say nothing about the Moon, which shifts about thirteen degrees a day and can change sign inside a single 27 July. They say nothing about the ascendant, which moves through a sign roughly every two hours and depends on the latitude of the birthplace as well as the clock.
That is the useful thing to take from the classification. It is precise about the Sun and silent about everything else, and a description of a person built from it alone is a description of one twelfth of the population. The widget above starts closing that gap by returning your exact degree and your distance from the nearest boundary once it has your year, hour and place.
Questions people ask about this
What does fixed fire mean for 27 July?
Fixed places Leo in the middle of a season and fire groups it with Aries and Sagittarius at a hundred and twenty degrees apart. Both are structural classifications before they are descriptions.
Is 27 July always Leo?
Yes. The Sun sits between about three and a half and five degrees of Leo in every year sampled at noon, roughly four days past the Cancer boundary.
Why does it matter that the Sun rules Leo?
Because a planet in the sign it governs is in domicile, which the tradition reads as expression without obstruction. It is an interpretive convention rather than a prediction.
Which decan is a 27 July Sun in?
The first decan of Leo, from zero to ten degrees. Chaldean tables give it Saturn, and the triplicity scheme keeps it with the Sun.
Do mode and element describe my personality?
They describe the position of a sign in the circle. The character readings attached to them are interpretive tradition, and they apply to a twelfth of people at a time.
What would tell me more than the sun sign?
The Moon and the rising sign, both of which change within a day. Neither can be worked out from the date alone, so both need your birth hour and birthplace.