One record per aspect. The origin says what kind of thing each value is; the source says where it came from; the limit says what it cannot tell you.
Position for the simulation time
Mercury's position is computed for the simulation instant by astronomy-engine, an analytic ephemeris model. There is no snapshot to age: the same code gives the same answer for any date.
Methodastronomy-engine (analytic planetary and lunar model; Sun through Pluto and the Moon)
UncertaintyRoughly arcminute-level against JPL ephemerides for 1700 to 2200; fixture tests compare selected dates with Horizons.
LimitPositions in the 3D scene are heliocentric J2000 equatorial coordinates; observer-facing tables are apparent, of date, and topocentric (see the frame statements).
Physical data
Undocumented
Bulk properties
Mercury: mean radius 2,439.7 km; mass 3.301 × 10^23 kg. These values are bundled with the object record and drive the rendered size.
SourceBundled object record
LimitThe object catalog does not record where these values came from; treat them as unverified until the record is completed.
MESSENGER MDIS observations
Monochrome morphology and optional enhanced spectral color. Original image shadows remain; independent MESSENGER DEM slopes use true-scale elevations. Not current or natural-color photography.
MethodThis describes the displayed appearance only; it does not certify catalog dimensions, orbital elements or unobserved geology.
Description and facts
The short description and the fact list are written by the Space Time authors for orientation. They are not quoted from a catalog field and carry no citation of their own.
SourceSpace Time editorial text
LimitBackground reading is linked under Further reading; it is not the source of the displayed numbers.
Space Time