double planet
Let an agent handle double planets by definition, examples, barycentre, and the debate over classification, with attributed views.
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 handle double planets by definition, examples, barycentre, and the debate over classification, with attributed views.
A binary system of two planetary-mass bodies orbiting each other, often defined informally as a pair whose common centre of mass lies outside both bodies; Pluto and Charon are commonly cited, while the Earth-Moon case is debated. The IAU has no formal definition.
What it is for: Classifying paired planetary bodies in planetary science.
It can be explain the barycentre criterion; list proposed examples; summarise the classification debate; compare with moons and binary asteroids.
Distinguishing features
Two planetary-mass bodies
Comparable masses
No formal IAU definition
Debated classification
What it looks like
Two comparable bodies orbiting a common point, seen in images and diagrams.
How it is recognised
Barycentre outside the larger body
Pluto and Charon
Binary stars are stellar systems
Related models
is a kind of - category
has example - example
is defined using - criterion
is contrasted with - related class
In practice
Families and kinds
dwarf planet binaries
proposed planet-moon pairs
binary trans-Neptunian objects
binary asteroids (related)
Standards and regulation
IAU planet and dwarf planet definitions (2006)
Failure modes and hazards
Presenting an informal term as official
Oversimplifying the barycentre criterion
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.
Definition What counts.
Definitions are informal.
Criterion
Barycentre.
Criterion
Barycentre criterion.
- Where is the barycentre of this pair? measurement
- Does the criterion depend on distance as well as mass? boundary
Status
Official or not.
Status
Official status.
- Is double planet an official IAU category? provenance
- Which authors use the term? provenance
Examples Proposed pairs.
Examples are debated.
Pluto-Charon
Classic example.
Pluto-Charon
Pluto-Charon.
- Why is Pluto-Charon often called a double dwarf planet? definition
- What did New Horizons observe? provenance
Earth-Moon
Debated case.
Earth-Moon
Earth-Moon.
- Why do some authors call Earth-Moon a double planet and others not? provenance
- Where is its barycentre? measurement
Physics Dynamics.
Orbits follow physics.
Orbit
Mutual orbit.
Orbit
Mutual orbit.
- What are the orbital period and separation of the pair? measurement
- Are they tidally locked? definition
Origin
Formation.
Origin
Formation.
- How might the pair have formed, according to models? provenance
- How certain is it? boundary
Related Other binaries.
Binaries occur at many scales.
Asteroids
Binary asteroids.
Asteroids
Binary asteroids.
- How do binary asteroids differ from double planets? boundary
- Which examples are known? provenance
Teaching
Explaining.
Teaching
Teaching.
- How can the barycentre idea be explained simply? action
- Which simulations help? provenance
What the second pass must settle
- Should examples be separate entries?
- How should competing definitions be recorded?
- How should binary asteroids be linked?