Refer to the following table to generate the number of planets for each star. First determine whether there are any planets; for multiple star systems, roll only once for the whole system, using the spectral type of the primary star. If the result is affirmative, generate the number of planets for each star, based on the star's own spectral type.

Planetary systems can be divided into three zones; different types ofplanet will tend to form in each zone. Zone A is the inner or hot zone; zone B is the intermediate or life zone; and zone C is the outer or cold zone (in our system, Mercury and Venus are in zone A, Earth and Mars are in zone B, and the asteroids and outer planets are in zone C). The following table gives the number of planets in each zone for main sequence and giant stars; for white dwarfs, neutron stars, and black holes, all planets are in zone C.

At this point, if the star is a member of a multiple system, remove the outermost D6+1 planets (but use the original number of planets to determine which zones the remaining inner planets are placed in). This may leave the star with no planets.

For each planet, three parameters are determined: Type, size, and number of moons. Roll D100 and refer to the following table for planet type, then generate the size. If the star is type F, G, or K (main sequence only, not giants or white dwarfs), use the second column for zone B; otherwise, use the first column.

Neutron stars and black holes will never have planets with atmospheres (too cold); treat a result of H as J.

Size and number of moons are not applicable to asteroid belts. Giant planets have 2D10 moons. For terrestrial planets (all the remaining types), roll a D10; the planet has no moons on 1 to 4, one moon on 5 to 7, two moons on 8 or 9, and three moons on 10.

ASTEROID BELT: A collection of rocks that never combined to form a planet. Usually there will be a handful of large asteroids a few hundred kilometres across, and a vast number of smaller objects.

GIANT: A huge planet consisting mainly of hydrogen, ranging from ten to a thousand times the Earth's mass. Example: Jupiter.

VACUUM/ROCK: A small, rocky planet with no atmosphere. Example: Mercury.

VACUUM/ICE: Similar to vacuum/rock, but composed mainly of ice rather than rock; found only in the outer part of a system. Example: Pluto.

DESERT: Comparable in size to Earth, but with a barren surface and a thin, inert atmosphere. Example: Mars.

HOSTILE: Comparable in size to Earth, with an atmosphere containing no oxygen but with some other active component, or having some other feature which makes the planet's surface unpleasant, such as extreme volcanic activity. Hostile planets may occasionally have native life forms, but they will be based on a very non-Earthlike biochemistry. Example: Venus.

MARGINAL: Almost Earthlike, with oxygen in the atmosphere, but with some serious problem that makes it an unpleasant place to live, such as very high or low temperature, atmospheric pressure, or oxygen level; traces of some toxic gas in the atmosphere; dangerous volcanic activity; or high radiation level. No examples in our solar system.

EARTHLIKE: Oxygen atmosphere, temperatures not too far outside the human comfort zone, and a reasonably stable surface. Note that the presence of oxygen in the atmosphere necessarily implies the presence of life (oxygen is too reactive to occur in large amounts from geological processes alone, and would disappear in a relatively short time if life were to become extinct). Example: Earth.

The details of a system's planets can be conveniently written using the code letter for the type, the size in thousands of kilometres, and a dot followed by the number of moons, if any. Asteroid belts are simply indicated by an "A" with no numbers (and are not counted towards the "official" number of planets). Use slashes to mark the zone boundaries. Here are some examples, using our solar system and an imaginary one generated for Alpha Centauri.

Sun (G2)

9 planets: R5 H12 / E13.1 D7.2 / A G140.16 G120.18 G50.15 G50.8 J2.1

Alpha Centauri (G2,K0,M5)

(A) 6 planets: R9.3 H8 / H10 M15.2 / J5.1 G110.9

(B) 2 planets: R10.2 / H8 /

(C) 1 planet: H17.1 / /