A starship departs from the satellite of a Brown Dwarf orbiting the supergiant Antares.
(scene rendered by Constantine Thomas in Lightwave 7.5 and POVRay 3.02)

Welcome to the Worldbuilding Hub! The goal of this site is to serve as a repository of resources and articles (written by myself) to help people add physical realism to their fictional worlds and star systems – as such it is useful for any sci-fi project (be it a book, a setting, or an RPG) and is often quite educational in places.


Articles/Resources on this site…

  • EDG Realistic World Generation rules 2.3. These are my rules for generating realistic main worlds (and some other elements of planetary systems) – they are similar to the Classic Traveller worldgen rules but are expanded greatly from that. It includes a primary star generation system, orbital placement and physical and social stats generation.
  • Stellar Mapping. This somewhat mammoth project is a complete rewrite of my previous “Realistic Astrography” page, and now includes Equatorial to Galactic co-ordinate conversion files, the complete RECONS (2012) and DENSE star lists, as well as all the data from the Hipparcos, Gliese 3, and Yale catalogues for stars out to 300ly from Sol! These maps and data will be useful for any Near-Sol sci-fi endeavour!
  • Revised Stellar Generation Tables (v3.0). (PDF) These are revised star generation tables (a la book 6) that generate realistic star systems (both for existing systems and for new ones) – among other things, the statistical distribution of the stars is much closer to reality, so you actually have a lot more red dwarfs than FGK main sequence stars. And finally, you won’t have any more headaches trying to figure out how the hell a habitable planet can exist around a randomly generated red giant or white dwarf!
  • How to calculate Stellar Magnitudes. (PDF) How to calculate how bright a star would look from a given viewpoint. Warning: contains logarithms, but also has examples! Useful for adding a bit of background flavour to your worlds (particularly when you realise that a companion star is actually bright enough to turn night into day…). Doesn’t work for planets though – unfortunately that’s a lot more complicated!
  • How to calculate Angular Diameters. (PDF) How to calculate how big a star (or planet) would look in the sky, from a given viewpoint. Warning: contains maths (but it’s not too hard). Also useful for adding some background flavour to your worlds.
  • Stellar Characteristics and Evolution. (PDF) A qualitative summary of star types and sizes, and a detailed explanation of stellar evolution. There is some discussion about logarithms but it’s not too painful for the math-phobic, and it should still prove useful for getting your head around how stars evolve and how that should affect planetary systems. UPDATED! – now includes an HR Diagram to help explain things a bit better!


    My RPG Books

    I’ve co-authored a couple of (well-received) SF RPG supplements over the years for which I did a lot of world-building. I came up with the realistic physical data and descriptions for the Katringa system in Spica Publishing’s System Book 1: Katringa, and wrote the extraterrestrial oceanography chapter in SJG’s Transhuman Space: Under Pressure (doing quite a bit of original research on how technology would work in Europa’s ocean in the process!). The Titan section of Under Pressure differs from reality since at the time of writing we hadn’t received data from Cassini about Titan’s hydrocarbon lakes, so we went with the best guess at the time (a large equatorial methane sea)!

    System Book 2: Xibalba, by Constantine Thomas (2013).

    A body drifts in the vacuum of space near the ruins of a habitat, dimly illuminated by the cooling corpse of a star. Strange noises echo down empty corridors. Ghostly figures appear outside spaceship windows. Voices from the past and future call for help on the radio. Ships go missing without a trace in the darkness.

    Are you brave enough to explore Xibalba?

    System Book 2: Xibalba includes a complete planetary system around a white dwarf star compatible with the current edition of the Traveller or any other SF RPG, designed for use in an existing campaign or as the focal point of an adventure. Inexplicable events plague the inhabitants of the system – are they really haunted by the ghosts of the dead, or is there a more rational explanation for the manifestations?

    System Book 1: Katringa, by Constantine Thomas and Richard Hazlewood (2010). System Book 1: Katringa is the first in a series of books from Spica Publishing that describes a complete planetary system and its society, designed for use with Traveller from Mongoose Publishing (but can be used with any other science fiction RPG as well).

    Katringa is a small, cold world with an exotic atmosphere located off the main trade routes. It is a former corporate mining colony run by Horizons Unlimited corporation that is gradually being allowed more independence over time, although corruption still pervades the government. The book contains a realistic planetary system designed using current astrophysical knowledge, full details of the worlds in the system (including the mineral-rich Idowa Belt, the gas giants Accra and Yendi and their moons, and Olufemi and the Outer Asteroids), a complete physical description of the planet Katringa, including a detailed breakdown of its geographical features and timekeeping system, details on Katringa’s society and important NPCs, Adventure Seeds, and detailed asteroid mining rules!

    Transhuman Space: Under Pressure, by David Morgan-Mar, Constantine Thomas and Kenneth Peters (2003). This supplement for SJG’s Transhuman Space roleplaying game (for GURPS 3e) covers the ocean environment of the 22nd Century – the teeming seas of Earth, the newly terraformed waters of Mars, the moon-spanning ocean under the ice of Europa, and the methane lakes of Titan. Ocean arcologies, mining operations and terrorist foes, and adventure and intrigue in an environment far more hostile than mere space.

    This book also includes new character templates — including new parahumans, bioroids, cybershells, and uplifted animals designed for aquatic existence — and modular design rules for aquatic vehicles, compatible with the system in Transhuman Space: In The Well.