planet
Let an agent handle planets by definition, orbit, physical properties and discovery method, and deal with the boundary cases such as dwarf planets and unconfirmed exoplanets.
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 planets by definition, orbit, physical properties and discovery method, and deal with the boundary cases such as dwarf planets and unconfirmed exoplanets.
A celestial body that orbits a star or stellar remnant, is massive enough for its gravity to make it nearly round, and has cleared its orbital neighbourhood, following the IAU 2006 definition for the Solar System; exoplanets use similar working criteria.
What it is for: Understanding planetary systems, the Earth and the potential for life elsewhere.
It can be observe it, directly or by transit and radial velocity methods; characterise it, for mass, radius, orbit and atmosphere; explore it, with spacecraft; name it, under IAU rules.
Distinguishing features
Orbits a star, unlike a moon
Has cleared its orbit, unlike a dwarf planet
Does not fuse hydrogen, unlike a star
Exoplanet status can be candidate, confirmed or disputed
What it looks like
Solar System planets appear as bright, steady points that move against the stars; exoplanets are almost never seen directly.
Physical character
mass: 0.055-318 Earth masses - Mercury to Jupiter; exoplanets up to about 13 Jupiter masses
orbital period: hours to thousands of years time
How it is recognised
Steady light and motion along the ecliptic
Visible discs in a telescope for Solar System planets
Exoplanets are detected indirectly, as dips in starlight or stellar wobble
Related models
is a kind of - a major class
orbits - planets belong to planetary systems
has - natural satellites are separate entries
is confused with - Pluto and others fail the cleared-orbit criterion
In practice
Families and kinds
terrestrial planets
gas giants
ice giants
exoplanets: hot Jupiters, super-Earths, mini-Neptunes
rogue planets
Identifiers
exoplanet name host star plus letter, such as 51 Pegasi b standard designation
NASA Exoplanet Archive entry archive record confirmed exoplanets
Standards and regulation
IAU Resolution B5 (2006) definition of planet
IAU naming rules for exoplanets
COSPAR planetary protection policy
Failure modes and hazards
Treating candidates as confirmed exoplanets
Mixing Solar System and exoplanet definitions
Contaminating other worlds, which planetary protection prevents
Also called
+19
Where this came from
wikidata · CC0 1.0
Also registered as vr.tr.planet-object
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 and status Is it a planet.
Planet status follows a definition with edge cases.
Criteria
IAU and exoplanet criteria.
Status criteria
Which criteria it meets.
- Which definition of planet applies here, and does the object meet it? definition
- Is it a dwarf planet or a brown dwarf instead? boundary
Confirmation
Candidate or confirmed.
Confirmation status
The confirmation state.
- Is this planet confirmed, and by which method? provenance
- Has its existence been disputed? provenance
Orbit Its path around the star.
Orbit decides climate and observability.
Orbital elements
Period, distance, eccentricity.
Orbital data
The orbital parameters.
- What are its orbital period, distance and eccentricity? measurement
- Is it in the habitable zone? boundary
System
Host star and siblings.
System context
The host star and other planets.
- Which star does it orbit, and what else is in the system? definition
- Are there resonances with other planets? measurement
Physical properties Mass, radius and atmosphere.
Physical properties decide what kind of world it is.
Bulk properties
Mass, radius, density.
Bulk data
Measured bulk values.
- What are its mass, radius and density? measurement
- Which values are measured and which inferred? provenance
Atmosphere and surface
Composition and conditions.
Atmosphere data
Atmosphere and surface data.
- What is known about its atmosphere and surface? measurement
- How was that measured? provenance
Exploration Missions and protection.
Exploration produces most data and carries planetary protection duties.
Missions
Spacecraft and telescopes.
Missions
Missions that studied it.
- Which missions have studied this planet? provenance
- Which are planned? provenance
Planetary protection
Avoiding contamination.
Protection category
The planetary protection category.
- Which planetary protection category applies to missions here? provenance
- What does it require? action
What the second pass must settle
- Should exoplanets be registered as instances linked to host stars?
- How should disputed and retracted exoplanets be marked?
- Should the registry adopt a working exoplanet definition?