Faut-il abandonner le zodiaque aux astrologues. Par Serge Bret-Morel.

The conference provides a valuable critical analysis of the definitions of the zodiac, a topic that is often taken for granted. Bret-Morel’s approach is methodical: he collects definitions from various astronomical sources and highlights inconsistencies. He demonstrates that the zodiac is not a well-defined astronomical concept but rather a cultural construct with multiple interpretations. The argumentation is solid, as he supports his claims with examples and references to specific sources, such as an article by Chapiro from 1977. He also explains the physical basis for the zodiacal band, which adds scientific rigor. However, the talk is based on a review of popular sources rather than peer-reviewed literature, which limits its academic weight. Additionally, while he mentions that he will discuss the history and diagrams in other talks, this presentation focuses on definitions, leaving some aspects unexplored. The title is appropriate, as it directly addresses the question of whether astronomers should cede the zodiac to astrologers. Overall, the talk is informative and thought-provoking, but it could benefit from more explicit references to academic sources and a deeper exploration of the historical context.

The title accurately reflects the content, which questions the definition and use of the zodiac in astronomy versus astrology.

8/10

The speaker is a former astrologer turned skeptic, and the talk is based on a systematic review of definitions from astronomical sources. The content is well-structured, with clear explanations and references to historical and scientific context. However, the lack of peer-reviewed sources and the reliance on popular astronomy websites and books slightly reduces the score.

Markers derived by PSI from the transcript: the creator did not define chapters.

• 00:00Introduction and thanks to Ciel & Espace and Alain Sirou.
• 02:00Introduction of the topic: the 13th constellation Ophiuchus and its prevalence in media.
• 05:00Explanation of the ecliptic and the fact that the Sun traverses 13 constellations.
• 10:00Discussion of the astrological zodiac of signs and the speaker's background in astrology.
• 15:00Presentation of survey results: multiple definitions of the zodiac among the audience.
• 20:00Introduction of the definition involving 25 constellations traversed by the Sun, Moon, and planets.
• 25:00Physical explanation of the zodiacal band: solar system formation on a disk and planetary orbits.
• 30:00Discussion of the Moon and planets' proximity to the ecliptic, leading to the band's width.
• 35:00Mention of Chapiro's 1977 article listing constellations traversed by celestial bodies.
• 40:00Conclusion and preview of upcoming talks on the history and diagrams of the zodiac.

• Chapiro's article (1977) — Mentioned as a source that lists constellations traversed by the Sun, Moon, and planets.

• Zodiac - Wikipedia — Supports the idea that the zodiac has multiple definitions and historical origins.

• IAU constellation boundaries — The IAU defines constellations as regions of the sky, which may conflict with the idea of a zodiacal band.