Sesquicentennial

Definition

Sesquicentennial literally means a 150th anniversary or a period of 150 years. It is a historical and calendrical term rather than a standard aspect, placement, or predictive technique in classical or modern astrology. It should not be confused with the sesquiquadrate, a 135-degree aspect, or the quincunx, an aspect of 150 degrees.

Astrological Meaning

When a sesquicentennial is discussed astrologically, the term usually identifies the 150th anniversary of an event, institution, or founding chart. An astrologer may compare the original chart with the anniversary chart, examine transits to the founding positions, or consider relevant planetary returns and longer cycles. The number 150 alone does not supply a universally accepted interpretation. Meaning depends on the chart being studied, the planets activated, their aspects, and the historical context.

Why It Matters

Recognizing the term’s limited technical status prevents confusion between elapsed years and angular distance. A 150-year commemoration may offer a useful occasion for mundane or historical chart analysis, but it is not automatically a distinct astrological cycle. Clear terminology helps readers determine whether an astrologer means an anniversary, a 150-degree quincunx, or the similarly named 135-degree sesquiquadrate.

Related Encyclopedia Entries

• Traditional Astrology
• Astrological Terminology
• Natal Chart