Systems and how to Read Them

In Traveller, you will be traveling between systems. Each system has its own hex on the subsector map and a corresponding data sheet. As such, it is quite important to be able to understand what the hexes and data sheets are telling you. This document is provided to aid you in this endeavor!

In Traveller terms, a system is about a parsec across and hex-shaped. Each system will generally only have one inhabitable world (if any) and most have a gas-giant. The following image should help you in identifying the system at a glance on the subsector map.


A system data sheet will have a lot of information on it, and thus it will be explained as you read. We will use Thoria from the first adventure as the example. Text {like this} was added to help guide you. Important note! The Imperium uses numbers to classify many things, for example, Thoria is a size class 5 planet. This is important to know at a glance how two planets may compare.

Universal World Profile
Thoria/0209/C557300-2 R P/R {Name/Sector/Planet Information/Travel Code}

Name: Thoria {The name of the system itself. If another name is in parenthesis, that is the habitable world or station}
System: 0209 {The system number}

Size: 5 – 8,000 km {How large the world is}
Gravity: 0.45 – Low Gravity {The gravity of the world. Low and High gravity worlds impose penalties}
Atmosphere: 5 – Thin {The world’s atmosphere rating. Certain atmospheres may impose penalties or even harm you without the proper gear}
Temperature: 9 – Temperate (0-30 degrees C) {The world’s average temperatures at the poles and equator}
Hydrographics: 7 – 66-75% (Earth-like) {The percentage of the world covered in water}

Population: 3 – Thousands {The number of people living on the world or station, usually does not include orbital facilities}
Government: 0 – None {The last recorded government the world had}
Rival Factions: {Any known rival factions to the government will be listed here, along with their strength}
Law Level: 0 {How strict the law on the planet is. Lower is more lax while higher is more strict}
Bans: None {What, if anything, is banned on-world}
Cultural Differences: {Any particularly strange customs will be listed here. Information about the customs can usually be found in the Information section at the end}

  • Unusual Custom: Offworlders

Starport: C {The class of starport, A being the best, E being the worst and X being non-existent}
Facilities: Research Base, Pirates {The various facilities in orbit around or on the planet. Pirates will not show up unless known about or discovered!}
TL: 2 – Primitive {The planet’s average tech-level. Note that it is entirely possible for a mideival society to have knights with laser lances and other odd technological inconsistences, especially if the government is involved}
Trade Goods: None {What you may expect to gain from trading with the planet}
Travel Code: Red {The planet’s Travel Code is an expression of how dangerous it is. Green is safe, Amber is warning, and Red is restricted}

Known Information: {The things an average traveler would know about the planet}
Thoria is a planet preserved by the Imperium. A Class C starport connected to a large research facility orbits the planet. Specifically, the research station is monitoring the advancement of the people on Thoria. The station’s name is Thoria Station. The people of Thoria are 7-8 feet tall on average and very slender. They have overdeveloped hearts and lungs to handle the atmosphere and thus do not suffer penalties for it. The occasional research visit has convinced the people that offworlders are gods from the skies (The Little Gods), come to visit. They are scattered around in a few different clans on one massive mega-continent.

Further Information: {Information you discover that was not included in the above}
A small pirate ship occasionally plagued the sector, until the crew of (SHIP NAME) took care of the problem. The researchers were secretly kidnapping people from the planet and subjecting them to various “culture shock” experiments to see how a culture with almost no technology could adapt to going up over ten tech-levels.

Systems and how to Read Them

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