astronomical object
Let an agent handle astronomical objects by class, designation, position and physical properties, and separate catalogue identity from physical nature.
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 astronomical objects by class, designation, position and physical properties, and separate catalogue identity from physical nature.
A naturally occurring physical body, association or structure in the observable universe, such as a star, planet, moon, asteroid, comet, nebula or galaxy.
What it is for: Organising what exists beyond the Earth atmosphere for observation, navigation and science.
It can be observe it, with telescopes across the spectrum; catalogue it, with designations and coordinates; measure it, for distance, mass, size and composition; name it, through the International Astronomical Union.
Distinguishing features
Natural; artificial satellites are a separate category
Identified by designations in catalogues, often several at once
Classified by physical nature: star, planet, galaxy and others
Position given in celestial coordinates with an epoch
What it looks like
From a point of light to an extended glowing cloud or a spiral of stars; many objects are only visible outside the visible spectrum.
Physical character
distance: from 384,000 km to over 10 billion light years distance
mass: from grams to 10^15 solar masses mass - meteoroids to galaxy clusters
How it is recognised
Point sources versus extended sources
Motion against the stars for Solar System objects
Catalogue designations such as M31, NGC 224, HD 209458
Related models
has kind - major classes with their own entries
is studied by - the discipline
is named by - naming authority
is confused with - human-made objects are different
In practice
Families and kinds
stars and stellar remnants
planets, dwarf planets and moons
small bodies: asteroids, comets, meteoroids
nebulae and interstellar clouds
galaxies and clusters
Identifiers
SIMBAD identifier catalogue designations cross-identifies objects
IAU Minor Planet number numeric asteroids and other small bodies
Standards and regulation
IAU naming rules and resolutions
ICRS celestial reference system
Outer Space Treaty on use and appropriation
Failure modes and hazards
Merging different catalogue objects with similar names
Using coordinates without the epoch
Near-Earth object impact risk, handled by planetary defence
Also called
+68
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.
Identity Names and designations.
Most objects have several designations; identity needs cross-identification.
Designations
Catalogue identifiers.
Designations held
All designations and the preferred one.
- Which designations identify this object? provenance
- Which name is officially recognised by the IAU? provenance
Class
What kind of object.
Classification
The physical class.
- What kind of object is it? definition
- How certain is the classification? measurement
Position and motion Where it is.
Position needs a reference frame and epoch.
Position
Coordinates.
Coordinates
The coordinates and epoch.
- What are its coordinates, in which frame and epoch? measurement
- How precise are they? measurement
Motion
Proper motion and orbit.
Motion data
Motion or orbital elements.
- How does it move, or what is its orbit? measurement
- Could it approach the Earth? boundary
Physical properties Distance, size and composition.
Physical properties describe what the object is.
Distance and size
How far and how big.
Distance and size
The distance and size estimates.
- How far away is it, and by which method was that measured? measurement
- How large and massive is it? measurement
Composition
What it is made of.
Composition
Composition from spectra or samples.
- What is it made of, and how is that known? measurement
- What is its temperature or luminosity? measurement
Observation How to see it.
Observation data are the source of everything else.
Visibility
When and where it can be seen.
Observability
Magnitude and visibility windows.
- How bright is it, and when is it visible from a given place? measurement
- What instrument is needed? definition
Data
Archives and surveys.
Data sources
Surveys and archives holding data.
- Which surveys and archives hold data on this object? provenance
- How current are they? provenance
What the second pass must settle
- Should catalogue objects be registered as instances with cross-identifiers?
- How should objects with uncertain classification be represented?
- Which coordinate epoch should the registry use?