The settled part
At noon in every year between 1930 and 2035, the Sun on 17 July stood between roughly twenty four and twenty five and a half degrees of Cancer. No hour of the day and no time zone changes the sign, because the crossing into Leo is around five days ahead and the year to year wobble is only about a day and a half.
The face is settled too. Twenty four degrees falls in the last ten degree band of Cancer, given to the Moon in the Chaldean count and to Jupiter through Pisces in the triplicity scheme. Sign, degree and face from a date alone is more than most sources will give you, and it is also where the date stops being useful. Every further question about a chart requires two more pieces of information that a calendar square cannot hold.
The Moon, which the hour decides
The Moon covers about thirteen degrees a day and changes sign every two and a bit days. On any particular 17 July it is likely to spend part of the day in one sign and, often enough, the evening in the next. Across a run of years it can be found in any of the twelve.
That is not a footnote. In traditional and modern practice alike the Moon carries much of the material about temperament and habit that people go looking for under their sun sign and do not find. A date cannot produce it. A date with an hour and a birthplace can. Where the hour is genuinely lost, the two candidate signs can at least be named, which is better than assuming one of them.
The horizon, which the place decides too
The ascendant is the degree of the zodiac rising in the east at the moment of birth. The whole circle turns past in a day, so it moves through roughly one sign every two hours and through all twelve between one midnight and the next. Being an hour out can be enough to change it.
Latitude matters as well, because signs rise at uneven speeds and the unevenness grows the further you go from the equator. Two births at the same clock time in Oslo and in Nairobi can have different rising signs. The houses are measured out from the ascendant, so they move with it. That is why an unknown birth time is a genuine limitation rather than a technicality, and why an honest chart drawn without one leaves the house ring blank.
Reading the sun sign at its proper weight
Roughly one person in twelve shares your sun sign, and everyone born within about a month of you in any year of history is among them. That makes it a real fact and a thin description, and treating it as the headline is exactly what makes birthday writing interchangeable.
The narrower version is more interesting. A cardinal water sign ruled by the Moon, at about twenty four degrees, in the face the older tables also hand to the Moon. Everything past that needs your year, your hour and your birthplace, which is what the widget above asks for before it returns your exact degree and your distance from the nearest boundary.
Questions people ask about this
What sign is 17 July?
Cancer, without qualification. Every year checked at noon from 1930 to 2035 gives the same answer, with roughly five days of the sign left to run.
What does the date not tell me?
The Moon sign, the rising sign, the house layout and the position of every faster moving planet. Those need the hour and the birthplace as well.
Can I get anything without a birth time?
Yes, up to a point. The Sun and the slower planets can be placed from the date alone, the Moon can usually be narrowed to two candidates, and the ascendant cannot be found at all.
How close is this date to Leo?
About five degrees, which is around five days. That is far enough that no birth hour or time zone can push a 17 July birth over the line.
Which decan does 17 July fall in?
The third decan of Cancer, covering twenty to thirty degrees, ruled by the Moon in the Chaldean order and by Jupiter under the triplicity scheme.
Is a sun sign meaningless then?
No, just narrow. It is a genuine position that the tradition reads in a particular way. The objection is to treating one factor as a whole description.