What the date does settle
At noon on 11 February the Sun has been between roughly twenty one and a half and twenty three degrees of Aquarius in every year from 1930 to 2035. That is a genuinely narrow answer, and it holds because the leap year cycle keeps the calendar in step with the orbit.
It also places the Sun in the third decan of Aquarius, the ten degree band that the Chaldean sequence assigns to the Moon. Sign, degree and decan are all fixed by the date alone, and that is the end of the list.
Those three facts are checkable. Any ephemeris for your year will confirm the longitude, and the decan follows arithmetically from it, so nothing here rests on interpretation.
The Moon depends on the hour
The Moon travels roughly thirteen degrees a day, which is about half a sign, so it changes sign every two and a bit days. On any given 11 February it is somewhere in one sign for part of the day and in the next for the rest, and which of the two you get depends on what time you were born and in which time zone.
Since the lunar sign shifts through the whole zodiac in a month, there is no relationship at all between this date and any particular Moon. Across a run of years, an 11 February birthday will have covered all twelve.
That is worth saying plainly, because a great deal of writing implies a link between a birth date and a lunar sign where none exists at all.
The rising sign depends on the minute and the place
The Ascendant is the degree of the zodiac coming over the eastern horizon at the moment of birth. The Earth turns once a day, so that degree moves through all twelve signs in twenty four hours and changes sign roughly every two hours. A birth at dawn and a birth at dusk on this date share a Sun and share nothing on the horizon.
Latitude matters too. Signs rise at very uneven speeds the further you go from the equator, so the same clock time gives different results in Edinburgh and in Nairobi. This is why a birth chart needs a place as well as a time.
The consequence is practical. Two people born on this date in the same hospital an hour apart will share a Sun to within a fraction of a degree and can still have different Ascendants, which is where most of the difference between their charts comes from.
Which is why the sun sign is the least personal part
The Sun is the slowest moving of the personal points, so everyone born within a day or so of you anywhere on Earth shares it. The faster a body or point moves, the more it separates one birth from another, which puts the rising sign and the Moon well ahead of the Sun on that measure.
The widget above uses your year, time and birthplace to give the exact solar degree, and reports how far you were born from the nearest sign boundary. For this date that margin is about a week either way, so the answer will be firm.
If the time is missing, the sign still holds and the rest is best treated as provisional rather than guessed at.
Questions people ask about this
What star sign is 11 February?
Aquarius, without qualification. The Sun is roughly three weeks into the sign and around a week from leaving it, so no year moves the answer.
Could I be a Pisces?
Not with this birth date. The Sun reaches Pisces around 18 or 19 February, which is several days later, and that boundary does not drift far enough to reach 11 February.
What Moon sign goes with this date?
There is no fixed answer. The Moon changes sign every two to three days, so it can be any of the twelve depending on the year, and often one of two depending on the hour.
Can I get my rising sign without a birth time?
Only as a range. Some approaches narrow it down using known life details, but the honest answer is that an unknown time leaves the Ascendant unresolved.
How precise is the solar degree here?
To within about a degree and a half across the last century at noon, and to a fraction of a degree once your own year and hour are supplied.
Does the third decan change anything about the sign?
It qualifies rather than overrides it. Tradition reads the last third of Aquarius as the more inward and retrospective part of the sign, which is interpretation rather than a measurable difference.