great circle
Let an agent explain great circles and their properties, relay uses in navigation, geodesy and astronomy from mathematics and navigation sources, describe the celestial circles the registry aliases name, and distinguish great circles from small circles, rhumb lines and lunar mansions.
Research draft, second pass
A second pass drafted this model: the structure a model of this thing needs, and what is known about it in the world. The line under this one says how the second half was obtained - researched against sources, or recalled without web access, in which case nothing here was read anywhere and every claim is a lead to verify. Unreviewed either way.
written by Claude from model knowledge without web access - no source was read, every claim is a lead to verify
Researched by: Claude
Purpose and description
Let an agent explain great circles and their properties, relay uses in navigation, geodesy and astronomy from mathematics and navigation sources, describe the celestial circles the registry aliases name, and distinguish great circles from small circles, rhumb lines and lunar mansions.
The largest circle that can be drawn on a sphere, formed by the intersection of the sphere with a plane through its centre, giving the shortest path between two points on the surface, used in navigation and aviation routes, and in astronomy as reference circles on the celestial sphere such as the celestial equator, celestial meridians, hour circles and vertical circles; on Earth, meridians are great circles; the registry aliases also list the lunar mansion, a division of the zodiac along the Moon s path, which is not a great circle itself, and the Riemannian circle, a related metric space notion.
What it is for: Shortest routes and celestial reference.
It can be explain properties; relay navigation and astronomy uses; describe celestial circles; distinguish related curves.
Distinguishing features
Through sphere centre
Shortest path
Divides sphere equally
Celestial reference
What it looks like
Not a visible object; a circle dividing a sphere into halves.
Physical character
Earth great circle length: about 40000 km
shortest path: geodesic on a sphere note
equator: the only parallel that is a great circle note
How it is recognised
Circle on a sphere with the sphere s centre
Meridian, celestial meridian, hour circle, vertical circle, Riemannian circle; lunar mansion as misfiled
Small circles do not pass through the centre; rhumb lines keep constant bearing; lunar mansions are zodiac divisions
Related models
is a kind of - in registry terms
is contrasted with -
includes -
is distinct from - a misfiled alias
In practice
Families and kinds
terrestrial meridians and the equator
great-circle routes
celestial equator and ecliptic
celestial meridians, hour circles and vertical circles
Riemannian circles in metric geometry
Standards and regulation
Aviation route planning practice
Failure modes and hazards
Confusing great-circle and rhumb-line navigation
Map projection distortion of routes
Registry alias lunar mansion misfiled
Also called
Where this came from
wikidata · CC0 1.0
Drafted structure
Bundle to layer to finding to question, as the second pass will find it: 4 bundles · 8 layers · 8 findings · 16 questions.
Understand What a great circle is.
Science.
Definition
Definition.
Definition
Definition.
- What is a great circle, and how does it differ from a small circle, rhumb line and lunar mansion? definition
- Is the question about geometry, navigation, astronomy or a misfiled alias? boundary
Kinds
Named circles.
Kinds
Kinds.
- What are meridians, celestial meridians, hour circles, vertical circles and Riemannian circles? definition
- Which entry fits the specific circle? action
Mathematics Mathematics.
Science.
Geodesic
Geodesics.
Geodesic
Geodesic.
- Why are great circles the shortest paths on a sphere, and how is distance computed? provenance
- Which references are standard? provenance
Trigonometry
Spherical trigonometry.
Trigonometry
Trigonometry.
- How does spherical trigonometry use great circles? provenance
- Which sources are cited? provenance
Applications Applications.
Application.
Navigation
Navigation.
Navigation
Navigation.
- How are great-circle routes used in aviation and shipping? provenance
- Which entry fits great-circle navigation? action
Astronomy
Astronomy.
Astronomy
Astronomy.
- How are great circles used as coordinates on the celestial sphere? provenance
- Which entry fits celestial coordinate system? action
Context History and registry note.
Context.
History
History.
History
History.
- How did ancient astronomers and navigators use great circles? provenance
- Which entry fits the history of navigation? action
Mansion
Lunar mansions.
Mansion
Mansion.
- What are lunar mansions, and why are they not great circles? provenance
- Which entry fits lunar mansion? action
What the second pass must settle
- Should hour circle and vertical circle be separate primary entries?
- How should navigation sources be linked?
- The registry alias lunar mansion is not a great circle and should be detached