Dictionary term
Argument of Periapsis
Direct answer
Argument of Periapsis is the angle within an orbital plane from the ascending node to periapsis in the direction of motion.
It orients the orbit’s nearest point within its plane.
It orients the orbit’s nearest point within its plane.
A scientific orientation to scale, light, or motion; the article supplies the precise definition.Quick reference
- Use when
- Use it only with the associated node, reference plane, and element set.
- Do not use it for
- It becomes undefined for special circular or equatorial cases without alternate elements.
- Reference category
- Astronomy & Skywatching
- Related terms
- Orbital Inclination, Longitude of Ascending Node, True Anomaly, Mean Anomaly
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The story behind Argument of Periapsis
The parameter emerged from classical methods for representing conic orbits.
Argument of Periapsis in spiritual tradition
Precise descriptions also admit where their coordinates break down.
Argument of Periapsis: fact and faith, kept distinct
This is a factual astronomy reference. It can support wonder at the created order without becoming a claim of fate, worship, or private revelation.
Argument of Periapsis in numerology
Argument of Periapsis is not a numerology claim. Any numbers attached to it should retain their ordinary scientific, calendrical, navigational, or historical meaning unless a separate symbolic interpretation is clearly labeled.
Why Argument of Periapsis matters
It completes the spatial orientation of an eccentric inclined orbit.
Argument of Periapsis at work: an example
Changing the argument rotates the ellipse inside an unchanged orbital plane.
Where interpretation stops
Argument of Periapsis is presented as sourced astronomy, calendrical, Earth-science, cultural, or instrument-history reference. Definitions should distinguish measured phenomena from civil convention and historical interpretation, preserve location and time dependencies, and avoid turning factual sky data into a deterministic personal claim.
Sources and editorial method
Research references used for this entry include:
- U.S. Naval Observatory: Astronomical Almanac Glossary - Definitions for astronomical coordinates, time, reference systems, and observable phenomena.
- NASA Science: Orbits and Kepler’s Laws - NASA explanation of orbital ellipses, orbital periods, and Kepler’s laws of planetary motion.
- Source
- The Great Almanac Dictionary
- Category
- Astronomy & Skywatching
- Also appears in
- Astronomy & Skywatching
- Aliases
- None listed
- Last updated
- 2026-07-16
Orient periapsis inside the orbit
Argument of Periapsis in a book is one thing; Argument of Periapsis in your own birth chart is your life. The Oracle casts your real chart and tells you what it means for your love, your work, and your year ahead, in conversation, free.
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More in Astronomy & Skywatching
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- Horizontal Coordinate System
- Meteor Shower
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Common questions
What is Argument of Periapsis?
Argument of Periapsis is the angle within an orbital plane from the ascending node to periapsis in the direction of motion.
How is Argument of Periapsis used in an almanac?
Use it only with the associated node, reference plane, and element set.
What should I avoid when interpreting Argument of Periapsis?
It becomes undefined for special circular or equatorial cases without alternate elements.
