The keyword phrase "september 11th is what zodiac sign" functions as an interrogative clause seeking to identify a specific proper noun. The zodiac sign for the date September 11 is Virgo.
In tropical Western astrology, a person's zodiac sign is determined by the position of the sun at their time of birth. The sun is located in the sign of Virgo from approximately August 23 to September 22. As September 11 falls squarely within this range, it is classified under this sign. Virgo is the sixth sign of the zodiac, an earth sign with a mutable modality, and it is ruled by the planet Mercury.
Consequently, an individual born on this date is considered a Virgo. This astrological classification is associated with traits such as being analytical, practical, meticulous, and modest. The influence of Mercury is thought to imbue Virgos with strong communication skills and a methodical, intellectual approach to life.