Planet/Asteroid Belt Generation

(Say, if the science appears cranky, blame me for it... for I must have been 13-14 years old when I created these rules... have fun! Mind you, I didn't have access to Traveller, GURPS Space, etc... only good old Star Frontiers and a huge astronomy book from the local library)

The generation of planets begin here. This is a long and complicated process. Planets/asteroid belts orbiting black holes, pulsars, and neutron stars bear no life (though exceptions may happen if the referee wishes). 

• Step 11: The number of planets orbiting a star was previously determined in Step 4 of Star Map Generation. To determine the orbit numbers for each planet, roll percentile dice and consult the table below or choose accordingly.
  
  For example, you are determining three planets for a dwarf star (DW). According to the green shaded squares for the DW column, planets will likely be found in that orbit range. You roll 02, 26, and 93. Referring to the 1d100 column, since a result of 93 lies beyond the green squares described for a DW star, you can either reroll your result or choose an appropriate row (for example, 55-61 is valid result for a DW star). 
  
  The final results are taken to be 02, 26, and 60 (rerolled). Orbit numbers are assigned arbitrarily for these and they are 5 (0.4 Earth year), 34 (10.9 Earth years), 83 (169 Earth years).
  
  Note: 
  1. Our Main Sequence (MS) Star - the bright Sun - has a maximum known orbit number of 112 which translates to 258 years. Coincidentally, Pluto's sidereal period is about 248.5 years long. 
  2. Planets orbiting MBH (Massive-), BH (Black Holes), PS (Pulsars), and NS (Neutron Stars) are probably captured debris from passing Long-period comets or from Oort Clouds. As such, they typically bear no life.
  3. Planets orbiting PS (Protostars) have not entered into a stable orbit yet.
     
     

Table 8: Orbit Number of Planets

1d100	Orbit Number	Sidereal Period (Earth Year)	MBH	BH	PS	NS	PR	DW	SD	MS	SG	G	SP
01 - 03	01 - 07	0.1 - 0.7
04 - 07	08 - 14	0.7 - 1.7
08 - 12	15 - 21	1.7 - 2.5
13 - 18	22 - 28	2.5 - 5.2
19 - 26	29 - 35	5.2 - 11
27 - 33	36 - 42	11 - 37
34 - 40	43 - 49	37 - 64
41 - 47	50 - 56	64 - 99
48 - 54	57 - 70	100 - 134
55 - 61	71 - 84	135 - 171
62 - 68	85 - 98	171 - 211
69 - 75	99 - 112	211 - 258
76 - 82	113 - 140	258 - 308
83 - 88	141 - 168	308 - 369
89 - 93	169 - 224	369 - 440
94 - 97	225 - 336	440 - 530
98 - 99	337 - 560	530 - 640
00	>560	> 640

• Step 12:  Repeat Step 11 for determining orbit numbers of asteroid belts.
  
  
• Step 13:  After determining the orbit numbers that planets will reside in, the next step will be to determine what type of planet can be found there. Use the tables below and determine a result by rolling the appropriate dice or by choosing a value. (For asteroid belts, proceed to step 14)
  
  For example, you have rolled a 50 which is a solid planet whose predominant surface is liquid (liquid does not necessarily always equate to water... think molten lava). You choose a rotational period that is 0.9 of an Earth day. Next you randomly decide that the planet has an equatorial diameter of 14235km. Making several dice rolls, you find that the planet has 3 satellites (moons) and 2 ring systems. Moving on to Table 9B, you decide that the planet's gravity is quite similar to Earth's - 1.12. Also, it has an atmospheric density of 12% (half as mild as planet Earth's weather). Finally, the planet has a density of 7.2 g/cm³.

Table 9A: Planetary Information

1d100	Type	Predominant Surface	Sidereal Rotation Period (Earth Days)	Equatorial Diameter (x 100 km)	Satellites	Ring Systems
01 - 34	Solid	Solid	0.4 - Infinity	0.5 - 120	30% - 1d4	03% - 1
35 - 54		Liquid	0.5 - Infinity	0.8 - 150	40% - 1d8	05% - 1d2
55 - 63	Giant Solid	Solid	0.5 - 100,000	120 - 600	35% - 1d10	09% - 1d2
64 - 70		Liquid	0.6 - 50,000	150 - 800	45% - 1d12	11% - 1d2
71 - 76	Gas	Solid	0.24 - 120	200 - 1000	50% - 1d12	30% - 1d3
77 - 84		Liquid	0.22 - 110	240 - 1200	55% - 2d10	35% - 1d3
85 - 89		Colloid	0.20 - 100	250 - 1400	60% - 3d8	40% - 1d3
90 - 92	Gas Giant	Solid	0.34 - 150	1000 - 6600	55% - 1d20	35% - 1d5
93 - 98		Liquid	0.32 - 130	1200 - 6800	60% - 2d20	40% - 1d5
99 - 00		Colloid	0.30 - 120	1400 - 7000	65% - 3d20	45% - 1d5

Table 9B: Planetary Information

1d100	Gravity (Earth = 1)	Atmospheric Density (Earth = 25%)	Planet Density (g/cm3)
01 - 34	0.01 - 6.00	01 - 02: 0% 03 - 08: 1d50%	1.1 - 9.0
35 - 54	0.01 - 5.80	01 - 02: 0% 03 - 10: 1d50% + 5%	1.1 - 10.0
55 - 63	0.02 - 8.50	01 - 02: 0% 03 - 10: 1d50% + 5%	1.1 - 8.0
64 - 70	0.02 - 8.30	01 - 02: 0% 03 - 12: 1d50% + 10%	1.1 - 9.0
71 - 76	0.40 - 10.40	3d20%	0.5 - 8.0
77 - 84	0.50 - 10.70	3d20% + 10%	0.5 - 9.0
85 - 89	0.60 - 11.00	3d20% + 20%	0.5 - 10.0
90 - 92	0.60 - 16.00	4d20%	0.5 - 6.0
93 - 98	0.70 - 16.50	4d20% + 10%	0.5 - 7.0
99 - 00	0.80 - 17.00	4d20% + 20%	0.5 - 8.0

• Step 14:  More to come soon...