A zodiac cusp is a popular label for a birthday near the transition from one Sun sign to another. Terms such as Aries–Taurus cusp and Libra–Scorpio cusp are widespread, yet in most conventional chart calculations the Sun occupies one longitude and therefore one sign at a particular instant.
What a cusp actually means
In strict astrology, a cusp commonly means the boundary of a house. The phrase sign cusp is used informally for the transition between adjacent signs. A person born on a changeover date may need an exact birth-time calculation to identify which sign contained the Sun. A single Sun cannot simultaneously occupy two different tropical signs in a standard birth chart.
Why adjacent sign descriptions sometimes resonate
Two neighboring signs can appear in one chart through Mercury, Venus, the Moon or the Ascendant, and aspects can reinforce traits traditionally attributed to a neighboring sign. Psychological identification with both sign descriptions also does not prove dual solar placement. Read the entire chart before explaining a personality by an invented blended sign.
The twelve transitions
The zodiac forms a circle, so Pisces–Aries is also a neighboring transition. Each change crosses a specific boundary and may coincide with a change of element or modality. Readers comparing cusp interpretations should first verify the astronomical sign change for their year.
Continue exploring
For the wider context, return to Zodiac Signs. Related topic pages in this section expand these ideas with placement-specific interpretations.