A reference index of astrological terms
The sun sign is the single most widely known element of a natal chart and the only one that can be determined from a birth date alone, which is why it is the basis of newspaper and website horoscope columns. In a full chart it is one factor among many and traditional practice does not privilege it.
The phrase describes a birth near a sign boundary. It has no technical standing: the Sun is in one sign or the other at any given instant, and the boundary is a point, not a zone. What the phrase usefully signals is that the date is close enough to a boundary that a table cannot be trusted.
The heavy popular emphasis on the sun sign is a consequence of publication format rather than doctrine. A daily column can address twelve groups and no more, and the sun sign is the only division a reader can look up without supplying a birth time or place. The ascendant, which changes every two hours, would produce a more differentiated reading and cannot be used for the purpose.
The Horoscope Hub is a reference work. Entries describe what practitioners do and what terms mean; they do not endorse astrological claims. Compiled by volunteers — see the contributor list and the editorial method.