1. This is a collaborative project - we do things through debate and consensus. There is no planet-master; there is no "leader".
  2. The planet we are inventing is, or could be, in our own universe. The basic laws and characteristics of this universe are what we know. 
  3. The location and "present" time of the planet are indeterminate. It could be in our own Galaxy or in another - its general characteristics are similar to where we are, since locating a con-planet in a galactic core would make it very difficult to work out the details of its life. Similarly, its temporal location is more or less our own - 10-15 Giga-years after the Big Bang. We want metals after all, and for that we need a first generation of starts having gone supernova.
  4. We have carbon-based life with the more evolved creatures breathing in oxygen and exhaling CO2. By implication, we'll need photosynthesis.
  5. Intelligent life being already in place, we don't actually want to follow the slow process of life > multicellular life > higher animals > apes.


  1. We shall have a multiple star system, with the planet we are creating going around one of the stars, which is (more or less) a Sun-like star. There is at least one other star in the system, which would be very bright in the sky of the planet (visible even in daylight), but would still appear as just a very bright star, and not a clear disk like the Moon. There may be another, smaller companion star and possibly other, star-like objects.
  2. There are other planets circling the star, including some large gas (Jupiter-like) planets. The system could have other components, including asteroids, comets etc.
  3. There is one large moon. There may be other, smaller moons.
  4. The planet is slightly larger than our own. Its atmosphere  is not so thick that the stars cannot be seen at night. Its gravity is not so high as to prevent largish animals from evolving.
  5. The planet has a magnetic field.
  6. The planet has vulcanism and continental drift.
  7. The planet has a reasonable ratio between surface water and land, no more than 80% for one, no less than 20% for the other.


  1. I see a serious disagreement on the number of sentient species. My personal feeling is that it is very hard for several intelligent species to coexist over significant periods of time, unless they occupy very different ecological niches (in fact, we could consider dolphins as sentient, and indeed they occupy a very different niche from us). Thus, either we go for the human-dolphin scenario (with dolphins maybe capable of tool use), or we go for several species that may be closely related but live on different continents. If this is what we choose, we could imagine a separation of species corresponding to what genus Homo had 1M-500K years ago, with divergent development on different continents ending up in two (or more?) species that cannot interbreed when they meet much later on. In any case, the map we draw for the continents will have to reflect the choices we make for the number and kinds of sentient life.