What the dates on this site mean
Our date labels use common Western tropical Sun-sign ranges. They are convenient calendar references, not an ephemeris calculation. The Sun's passage from one tropical sign to the next happens at a particular instant, and the calendar date attached to that instant depends on the year and time zone.
The date finder does not ask for a birth year, birth time or time zone. It therefore cannot determine an exact Sun position. Near a conventional transition, it shows both neighboring signs and asks you to consult a calculated chart if an exact placement matters to you. The extra day on either side is a cautious interface rule, not a measured uncertainty interval.
Twelve signs and the sky are different maps
Tropical astrology uses twelve equal divisions of the zodiac, anchored to the March equinox. Modern astronomical constellations are bounded regions of the sky with unequal sizes. The ecliptic is the Sun's apparent yearly path against the stars; it crosses thirteen astronomical constellations, including Ophiuchus.
That does not automatically insert a thirteenth sign into a twelve-part tropical system. It means the systems are describing different things. A diagram on this site shows equal symbolic divisions, rather than the boundaries of the astronomical constellations.
Why another site might give another answer
First check whether the site uses tropical or sidereal astrology. Sidereal systems use a stellar reference, and different sidereal conventions can also differ. Next check whether the result is a simple calendar table or a calculation using the birth details and a stated method.
For a birth near a sign change, an exact birth time and its correct historical time zone can matter. Do not silently substitute noon or today's time-zone rules and present the result as certain. If the birth time is unknown, retain that uncertainty rather than choosing the description that sounds most flattering.
What a “cusp” can and cannot tell you
A Sun position near a boundary is still a position in a specified coordinate system. Feeling that two sign descriptions fit does not determine that position, and a date table cannot establish a blended personality. You can read neighboring symbols for reflection without treating either as a factual assessment.
If you want only a place to begin reading, choose either relevant guide and see which question is useful. If you want an exact chart placement, use a calculation that states the zodiac system, birth details and treatment of unknown time. This site does not provide that calculation.
Sources & further reading
- IAU Office of Astronomy for Education: Zodiac
- IAU: the constellations
- Swiss Ephemeris 2.10: tropical and sidereal reference systems
- Astrology.com: conventional sign dates
Sources support the stated definitions and conventions. Exercises and examples are our own reflective applications.