Planetary Size

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Planetary Size: Worlds are classified according to their physical size.

Description (Specifications)

Planetary density and size are two primary factors when determining a planet's gravity.

Planetary Size Data

The following table outlines the UWP codes for the size of a body:

Planetary Size
Code Description Diameter (Km) Expected
R Planetary Ring Multiple < 1 Microgravity
(0.01 G or less)
Planetary Ring, Planetoid
D Debris 1+ < 200 Microgravity
(0.01 G or less)
Debris Field, Planetoid
0 Asteroid / Planetary Belt Multiple < 200 Microgravity
(0.01 G or less)
Planetoid Belt, Planetoid
S Very Small 200-799 Very Low Gravity
(400 km, 0.02g - 0.03g)
Very Small World
1 Small 800-2399 Very Low Gravity
(1,600 km, 0.05g - 0.09g)
Small World
2 Small (e.g. Luna) 2,400-3,999 Low Gravity
(3,200 km, 0.10g - 0.17g)
Small World
3 Small (e.g. Mercury) 4,000-5,599 Low Gravity
(4,800 km, 0.24g - 0.34g)
Small World
4 Medium (e.g. Mars) 5,600-7,199 Low Gravity
(6,400 km, 0.32g - 0.46g)
Meso World
5 Medium 7,200-8,799 Standard Gravity
(8,000 km, 0.40g - 0.57g)
Meso World
6 Medium 8,800-10,399 Standard Gravity
(9,600 km, 0.60g - 0.81g)
Meso World
7 Large 10,400-11,999 Standard Gravity
(11,200 km, 0.70g - 0.94g)
Macro World
8 Large (e.g. Venus / Terra) 12,000-13,599 Standard Gravity
(12,800 km, 0.80g - 1.08g)
Macro World
9 Large 13,600-15,199 Standard Gravity
(14,400 km, 1.03g - 1.33g)
Macro World
A (10) Huge 15,200-16,799 Standard Gravity
(16,000 km, 1.14g - 1.48g)
Big World
B (11) Huge 16,800 - 18,399 High Gravity
(17,600 km, 1.49g - 1.89g)
Big World
C (12) Huge 18,400+ High Gravity
(19,400 km, 1.9g - 2.0g)
Big World
SGG Small Gas Giant (no further codes) 40,000-120,000 Macrogravity
(2.01 G or higher)
Gas Giant
LGG Large Gas Giant (no further codes) 120,000-240,000+ Macrogravity
(2.01 G or higher)
Gas Giant
  • NOTE-1: The size code D ( Debris ) is non-standard. It is included to cover such cases as Comet Mid-Rift (Deneb 3234), which are less than 200Km, but not part of an asteroid belt, yet important enough to have mention.
  • NOTE-2: The gravity values are estimations based on a standard planetary density. Planets with less or more dense cores may have very different values from the suggested average.

History & Background (Dossier)

When the UWP was created, any number of planetological figures were considered for inclusion. Initial discussion led to 16 and 32-factor descriptive chains, but these were too many, especially for a Universal Code. Eventually the UWP was pared down to just eight factors. Of those eight factors, one of the most disputed was Planetary Size.

Size included many, many factors including:

  • Gravity
  • Physical measurement parameters
  • Planetary density
  • Tectonics
  • Vulcanism
  • etc.

See also

Universal world profile

§ == ( Please refer to the following AAB Library Data for more information: ) == §

References & Contributors (Sources)

This list of sources was used by the Traveller Wiki Editorial Team and individual contributors to compose this article. Copyrighted material is used under license from Far Future Enterprises or by permission of the author. The page history lists all of the contributions.