Meso World

Meso Worlds are worlds that have a diameter of between 5,600 km and 13,600 km.

• The term specifically relates to solid (rocky) planets.
• It describes a physical characteristic of the world.

Description / Specifications

Meso World is a very broad term used to describe the general size of a world. A meso world is likely to have a moderate surface gravity, depending on its density and mass.

• Meso means "middle" or "intermediate".

General size code categories:

• Size Codes 0 or S: Planetoid.
• Size Codes 1-3: Small World.
• Size Codes 4-8: Meso World.
• Size Code 9 or more: Big World.

Planetary Characteristics

General details for meso worlds are provided below:

Worlds may be up to 800 km smaller or 800 km larger than the mean diameter and still qualify as the same UWP size code.

Terra, the human homeworld, has an average density of 5.5 grams per cubic centimeter (abbreviated to 5.5 g/cm³).

• Low density worlds largely consist of stony materials. They have relatively low quantities of heavier elements such as iron within their structure.
• Average density worlds have moderate amounts of heavier elements within their structure.
• High density worlds have greater quantities of heavier elements within their structure.

Size Code	Mean Diameter	Low Density (3.5 g/cm³)	Average Density (5.5 g/cm³)	High Density (7.5 g/cm³)	Distance to Horizon
4	6,400 km	Mass: 0.080 Earths Surface Gravity: 0.315 G	Mass: 0.125 Earths Surface Gravity: 0.500 G	Mass: 0.170 Earths Surface Gravity: 0.685 G	Approximately 3.6 km
5	8,000 km	Mass: 0.150 Earths Surface Gravity: 0.395 G	Mass: 0.245 Earths Surface Gravity: 0.625 G	Mass: 0.335 Earths Surface Gravity: 0.855 G	Approximately 4.0 km
6	9,600 km	Mass: 0.260 Earths Surface Gravity: 0.475 G	Mass: 0.420 Earths Surface Gravity: 0.750 G	Mass: 0.573 Earths Surface Gravity: 1.020 G	Approximately 4.4 km
7	11,200 km	Mass: 0.315 Earths Surface Gravity: 0.570 G	Mass: 0.670 Earths Surface Gravity: 0.875 G	Mass: 0.915 Earths Surface Gravity: 1.195 G	Approximately 4.7 km
8	12,800 km	Mass: 0.620 Earths Surface Gravity: 0.630 G	Mass: 1.000 Earths Surface Gravity: 1.000 G	Mass: 1.350 Earths Surface Gravity: 1.360 G	Approximately 5.1 km

Note that different versions of the rules may have alternative definitions for Small Worlds, Meso Worlds, and Big Worlds.

History & Background

Meso Worlds retain a vast variety of atmospheres.

Probable Orbits

Meso worlds may be located within any region of a system. Meso worlds are occasionally moons of larger rocky worlds or gas giants.

See also

Star systems

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

• Star System
• Astrography

• Planetology
  • Axial Tilt
  • Inner World
  • Habitable Zone
  • Lagrange Point
  • Outer World
  • Orbital Eccentricity
  • Remote System
  • Far System

Contents

• Star
• Gas Giant
• Planet
• Main World
• Natural Satellite
• Planetoid
• Planetary Ring
• Satellite

Environment

• Asteroid Belt World
• Ellipsoid World
• Fluid World
• Garden World
• Gas Giant
• Hell World
• Ice World
• Locked World
• Ocean World
• Planetoid Belt World
• Rad World
• Satellite World
• Storm World
• Terran Prime World (Gaian or Garden) world
• Terrestrial World
• Twilight Zone World
• Vacuum World
• Water World

References & Contributors / Sources

This article is missing content for one or more detailed sections. Additional details are required to complete the article. You can help the Traveller Wiki by expanding it.

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 Mongoose Publishing or by permission of the author. The page history lists all of the contributions.

• Marc Miller. Worlds and Adventures (Game Designers Workshop, 1977).
• Marc Miller. Scouts (Game Designers Workshop, 1983), .
• Joe Fugate, J. Andrew Keith, Gary L. Thomas. World Builder's Handbook (Digest Group Publications, 1989).
• Terrance McInnes, Dave Nilsen. World Tamer's Handbook (Game Designers Workshop, 1994), .
• Martin Dougherty. A Guide to Star Systems (Mongoose Publishing, 2015), .
• Marc Miller, Robert Eaglestone, Don McKinney. Worlds and Adventures (Far Future Enterprises, 2019).
• Matthew Sprange. "Gas Giants, Planetoid, and other bodies." Journal of the Travellers' Aid Society volume 2 (2019): 80-85.
• Martin Dougherty. Referee's Handbook (Mongoose Publishing, 2021), 83-84.
• Geir Lanesskog. World Builder's Handbook (Mongoose Publishing, 2023).
• External Link: Beowolf's Libary Data Website ^{dead link} (relevance pending, as site has not been archived)
• Author & Contributor: Lord (Marquis) and Master Scout Emeritus Adie Alegoric Stewart of the IISS
• Author & Contributor: Lord (Marquis) and Master of Sophontology Maksim-Smelchak of the Ministry of Science