Thirty degrees, cut into three
Every sign spans thirty degrees and splits into three equal parts of ten, a scheme older than the popular sun sign column by a very long way. Egyptian sources divided the sky this way before the twelve sign zodiac reached its familiar form, and the divisions survived into Hellenistic practice as the decans.
The value of the scheme is that it separates people the sign lumps together. A Leo born in the third week of July and one born a month later share nothing in this respect, and only the band shows it.
Each band was originally tied to a group of stars that rose at a particular point in the night, which is where the name comes from. The stellar link faded and the ten degree arithmetic stayed.
Where 3 August lands
At noon across every year from 1930 to 2035, the Sun on this date has fallen between roughly ten and a quarter and about eleven and a half degrees of Leo. The whole of that window sits above ten degrees, so the second band holds regardless of year, and a birth at any hour of the day stays inside it.
The window is narrow for the usual reason. Each common year the date arrives a quarter of a day early relative to the Sun's return, and each leap day gives that time back, which keeps the position circling a fixed longitude rather than sliding through the sign.
Anyone born in the small hours falls a fraction below the noon figure for their year and anyone born late at night a fraction above, since the Sun advances a little under a degree a day. Neither extreme comes close to a band edge here.
Jupiter in the middle of Leo
The Chaldean sequence walks the seven classical planets in order of apparent speed, starting from Saturn at the first degree of Aries, and repeats around the whole zodiac. Landing on Leo it gives the first band to Saturn, the second to Jupiter and the third to Mars.
Jupiter inside a solar sign is read in the tradition as expansion on top of warmth: an inclination to make room for other people, to teach or to host, and a taste for the large gesture rather than the careful one. That is a convention carried down through the texts, not a finding, and it describes what the tradition attaches to the band rather than anything the date does to a person.
Because the whole noon window sits above ten degrees, no year of birth and no hour puts this date back into the first band, which is not true of the day before it.
The limits of a date
A sign, a degree band and a decan ruler are what this birthday supplies. The Moon is not among them, since it crosses about half a sign a day and can be in either of two signs depending on the hour.
The Ascendant is further out of reach again, because the zodiac turns past the horizon once a day and the rate depends on latitude, so any of the twelve can be rising. The widget above takes a year, a time and a birthplace, computes the exact solar degree instead of the range, and reports how far the birth stood from the nearest sign boundary.
Between them, the sign, the degree and the band make three checkable statements. Everything past that belongs to the chart rather than to the calendar.
Questions people ask about this
What decan is 3 August?
The second decan of Leo, from ten to twenty degrees. The noon position exceeds ten degrees in every year from 1930 onward, so the band applies whatever the year of birth.
What is the solar degree on this date?
Roughly ten and a quarter to about eleven and a half degrees of Leo at noon, depending on the year. The widget above narrows that to a single figure from your own details.
Who rules the second decan of Leo?
Jupiter, under the Chaldean order that runs the classical planets by apparent speed. The sign itself remains ruled by the Sun, so the band adds a second layer rather than replacing the first.
Is a 3 August birthday ever not Leo?
No. The Sun is eleven or twelve days into the sign on this date and the nearest ingress is weeks away, so the sign is fixed for every year and every hour.
Does the decan change what my sun sign means?
It narrows it. The sign covers a month of births and the band about a third of that, so the tradition treats the decan as a qualification on the sign rather than a competing description.
What does the date still leave open?
The Moon, which needs an hour of birth, and the rising sign and houses, which need an hour and a birthplace. The Sun is the one placement a date can fix on its own.