A new size scale for stellar systems

[Space Cadet]

Here is a new continum for planetary and subplanetary sizes in a stellar system. The method used to generate sizes is d100 producing a number from 0 to 99.

The probability of getting a planet is 3 out of 10. We will therefore need additional orbits to ensure that the star systems we generate aren't too sparse.

Here are the new orbit numbers

ORBITAL DISTANCES
orbt
00 = 7,500,000 km
01 = 15,000,000 km
02 = 22,400,000 km
03 = 29,900,000 km
04 = 37,400,000 km
05 = 44,900,000 km
06 = 52,300,000 km
07 = 59,800,000 km
08 = 71,000,000 km
09 = 82,300,000 km
10 = 93,500,000 km
11 = 104,700,000 km
12 = 115,900,000 km
13 = 127,200,000 km
14 = 138,400,000 km
15 = 149,600,000 km
16 = 172,000,000 km
17 = 194,500,000 km
18 = 216,900,000 km
19 = 239,300,000 km
20 = 284,200,000 km
21 = 329,100,000 km
22 = 374,000,000 km
23 = 418,900,000 km
24 = 508,700,000 km
25 = 598,400,000 km
26 = 688,200,000 km
27 = 777,900,000 km
28 = 957,400,000 km
29 = 1,137,000,000 km
30 = 1,316,000,000 km
31 = 1,496,000,000 km
32 = 1,855,000,000 km
33 = 2,214,000,000 km
34 = 2,573,000,000 km
35 = 2,932,000,000 km
36 = 3,650,000,000 km
37 = 4,368,000,000 km
38 = 5,086,000,000 km
39 = 5,804,000,000 km
40 = 7,240,000,000 km
41 = 8,676,000,000 km
42 = 10,110,000,000 km
43 = 11,550,000,000 km
44 = 14,420,000,000 km
45 = 17,290,000,000 km
46 = 20,170,000,000 km
47 = 23,038,000,000 km
48 = 28,780,000,000 km
49 = 34,530,000,000 km
50 = 40,270,000,000 km
51 = 46,016,000,000 km

The scale starts out small with 0 equal to a round object that is 1.5 meters in diameter. The formula used to generate these sizes is diameter = 6.5^(indx/10) * 1.5 meters. Diameter is expressed rounded off to 3 significant digits or tenths of a meter.

indx diameter
00 - 1.5 m
01 - 1.8 m
02 - 2.2 m
03 - 2.6 m
04 - 3.2 m
05 - 3.8 m
06 - 4.6 m
07 - 5.6 m
08 - 6.7 m
09 - 8.1 m
10 - 9.8 m
11 - 11.8 m
12 - 14.2 m
13 - 17.1 m
14 - 20.6 m
15 - 24.9 m
16 - 30.0 m
17 - 36.1 m
18 - 43.6 m
19 - 52.6 m
20 - 63.4 m
21 - 76.4 m
22 - 92.2 m
23 - 111 m
24 - 134 m
25 - 162 m
26 - 195 m
27 - 235 m
28 - 283 m
29 - 342 m
30 - 412 m
31 - 497 m
32 - 599 m
33 - 722 m
34 - 871 m
35 - 1.05 km
36 - 1.27 km
37 - 1.53 km
38 - 1.84 km
39 - 2.22 km
40 - 2.68 km
41 - 3.23 km
42 - 3.89 km
43 - 4.69 km
44 - 5.66 km
45 - 6.83 km
46 - 8.23 km
47 - 9.93 km
48 - 12.0 km
49 - 14.4 km
50 - 17.4 km
51 - 21.0 km
52 - 25.3 km
53 - 30.5 km
54 - 36.8 km
55 - 44.4 km
56 - 53.5 km
57 - 64.5 km
58 - 77.8 km
59 - 93.8 km
60 - 113 km
61 - 136 km
62 - 164 km
63 - 198 km - Small World (old Size S)
64 - 239 km - Small World (old Size S)
65 - 288 km - Small World (old Size S)
66 - 348 km - Small World (old Size S)
67 - 419 km - Small World (old Size S)
68 - 506 km - Small World (old Size S)
69 - 610 km - Small World (old Size S)
70 - 735 km - Small World (old Size S)
71 - 886 km - (old Size 1)
72 - 1,070 km - (old Size 1)
73 - 1,290 km - (old Size 1)
74 - 1,550 km - (old Size 1)
75 - 1,870 km - (old Size 1)
76 - 2,260 km - (old Size 1)
77 - 2,730 km - (old Size 2)
78 - 3,290 km - (old Size 2)
79 - 3,960 km - (old Size 2)
80 - 4,780 km - (old Size 3)
80.1 - 4,870 km - (old Size 3)
80.2 - 4,960 km - (old Size 3)
80.3 - 5,050 km - (old Size 3)
80.4 - 5,150 km - (old Size 3)
80.5 - 5,250 km - (old Size 3)
80.6 - 5,350 km - (old Size 3)
80.7 - 5,450 km - (old Size 3)
80.8 - 5,550 km - (old Size 3)
80.9 - 5,660 km - (old Size 4)
81 - 5,760 km - (old Size 4)
81.1 - 5,870 km - (old Size 4)
81.2 - 5,980 km - (old Size 4)
81.3 - 6,100 km - (old Size 4)
81.4 - 6,210 km - (old Size 4)
81.5 - 6,330 km - (old Size 4)
81.6 - 6,450 km - (old Size 4)
81.7 - 6,570 km - (old Size 4)
81.8 - 6,700 km - (old Size 4)
81.9 - 6,820 km - (old Size 4)
82 - 6,950 km - (old Size 4)
82.1 - 7,080 km - (old Size 4)
82.2 - 7,220 km - (old Size 5)
82.3 - 7,350 km - (old Size 5)
82.4 - 7,490 km - (old Size 5)
82.5 - 7,630 km - (old Size 5)
82.6 - 7,780 km - (old Size 5)
82.7 - 7,920 km - (old Size 5)
82.8 - 8,070 km - (old Size 5)
82.9 - 8,230 km - (old Size 5)
83 - 8,380 km - (old Size 5)
83.1 - 8,540 km - (old Size 5)
83.2 - 8,700 km - (old Size 5)
83.3 - 8,860 km - (old Size 6)
83.4 - 9,030 km - (old Size 6)
83.5 - 9,200 km - (old Size 6)
83.6 - 9,380 km - (old Size 6)
83.7 - 9,550 km - (old Size 6)
83.8 - 9,730 km - (old Size 6)
83.9 - 9,920 km - (old Size 6)
84 - 10,100 km - (old Size 6)
84.1 - 10,300 km - (old Size 6)
84.2 - 10,500 km - (old Size 7)
84.3 - 10,700 km - (old Size 7)
84.4 - 10,900 km - (old Size 7)
84.5 - 11,100 km - (old Size 7)
84.6 - 11,300 km - (old Size 7)
84.7 - 11,500 km - (old Size 7)
84.8 - 11,700 km - (old Size 7)
84.9 - 12,000 km - (old Size 8)
85 - 12,200 km - (old Size 8)
85.1 - 12,400 km - (old Size 8)
85.2 - 12,700 km - (old Size 8)
85.3 - 12,900 km - (old Size 8)
85.4 - 13,100 km - (old Size 8)
85.5 - 13,400 km - (old Size 8)
85.6 - 13,600 km - (old Size 9)
85.7 - 13,900 km - (old Size 9)
85.8 - 14,200 km - (old Size 9)
85.9 - 14,400 km - (old Size 9)
86 - 14,700 km - (old Size 9)
86.1 - 15,000 km - (old Size 9)
86.2 - 15,300 km - (old Size A)
86.3 - 15,500 km - (old Size A)
86.4 - 15,800 km - (old Size A)
86.5 - 16,100 km - (old Size A)
86.6 - 16,400 km - (old Size A)
86.7 - 16,800 km - (small Gas Giant)
86.8 - 17,100 km - (small Gas Giant)
86.9 - 17,400 km - (small Gas Giant)
87 - 17,700 km - (small Gas Giant)
87.1 - 18,100 km - (small Gas Giant)
87.2 - 18,400 km - (small Gas Giant)
87.3 - 18,700 km - (small Gas Giant)
87.4 - 19,100 km - (small Gas Giant)
87.5 - 19,500 km - (small Gas Giant)
87.6 - 19,800 km - (small Gas Giant)
87.7 - 20,200 km - (small Gas Giant)
87.8 - 20,600 km - (small Gas Giant)
87.9 - 21,000 km - (small Gas Giant)
88 - 21,400 km - (small Gas Giant)
88.1 - 21,800 km - (small Gas Giant)
88.2 - 22,200 km - (small Gas Giant)
88.3 - 22,600 km - (small Gas Giant)
88.4 - 23,000 km - (small Gas Giant)
88.5 - 23,500 km - (small Gas Giant)
88.6 - 23,900 km - (small Gas Giant)
88.7 - 24,400 km - (small Gas Giant)
88.8 - 24,800 km - (small Gas Giant)
88.9 - 25,300 km - (small Gas Giant)
89 - 25,800 km - (small Gas Giant)
89.1 - 26,300 km - (small Gas Giant)
89.2 - 26,700 km - (small Gas Giant)
89.3 - 27,300 km - (small Gas Giant)
89.4 - 27,800 km - (small Gas Giant)
89.5 - 28,300 km - (small Gas Giant)
89.6 - 28,800 km - (small Gas Giant)
89.7 - 29,400 km - (small Gas Giant)
89.8 - 29,900 km - (small Gas Giant)
90 - 31,100 km - (small Gas Giant)
90.1 - 31,700 km - (small Gas Giant)
90.2 - 32,300 km - (small Gas Giant)
90.3 - 32,900 km - (small Gas Giant)
90.4 - 33,500 km - (small Gas Giant)
90.5 - 34,100 km - (small Gas Giant)
90.6 - 34,800 km - (small Gas Giant)
90.7 - 35,400 km - (small Gas Giant)
90.8 - 36,100 km - (small Gas Giant)
90.9 - 36,800 km - (small Gas Giant)
91 - 37,500 km - (small Gas Giant)
91.1 - 38,200 km - (small Gas Giant)
91.2 - 38,900 km - (small Gas Giant)
91.3 - 39,600 km - (small Gas Giant)
91.4 - 40,400 km - (small Gas Giant)
91.5 - 41,100 km - (small Gas Giant)
91.6 - 41,900 km - (small Gas Giant)
91.7 - 42,700 km - (small Gas Giant)
91.8 - 43,500 km - (small Gas Giant)
91.9 - 44,300 km - (small Gas Giant)
92 - 45,200 km - (small Gas Giant)
92.1 - 46,000 km - (small Gas Giant)
92.2 - 46,900 km - (small Gas Giant)
92.3 - 47,800 km - (small Gas Giant)
92.4 - 48,700 km - (small Gas Giant)
92.5 - 49,600 km - (small Gas Giant)
92.6 - 50,500 km - (small Gas Giant)
92.7 - 51,500 km - (small Gas Giant)
92.8 - 52,500 km - (small Gas Giant)
92.9 - 53,500 km - (small Gas Giant)
93 - 54,500 km - (small Gas Giant)
93.1 - 55,500 km - (small Gas Giant)
93.2 - 56,600 km - (small Gas Giant)
93.3 - 57,600 km - (small Gas Giant)
93.4 - 58,700 km - (small Gas Giant)
93.5 - 59,800 km - (small Gas Giant)
93.6 - 60,900 km - (small Gas Giant)
93.7 - 62,100 km - (small Gas Giant)
93.8 - 63,300 km - (small Gas Giant)
93.9 - 64,500 km - (large Gas Giant)
94 - 65,700 km - (large Gas Giant)
94.1 - 66,900 km - (large Gas Giant)
94.2 - 68,200 km - (large Gas Giant)
94.3 - 69,500 km - (large Gas Giant)
94.4 - 70,800 km - (large Gas Giant)
94.5 - 72,100 km - (large Gas Giant)
94.6 - 73,500 km - (large Gas Giant)
94.7 - 74,900 km - (large Gas Giant)
94.8 - 76,300 km - (large Gas Giant)
94.9 - 77,700 km - (large Gas Giant)
95 - 79,200 km - (large Gas Giant)
95.1 - 80,700 km - (large Gas Giant)
95.2 - 82,200 km - (large Gas Giant)
95.3 - 83,800 km - (large Gas Giant)
95.4 - 85,400 km - (large Gas Giant)
95.5 - 87,000 km - (large Gas Giant)
95.6 - 88,600 km - (large Gas Giant)
95.7 - 90,300 km - (large Gas Giant)
95.8 - 92,000 km - (large Gas Giant)
95.9 - 93,700 km - (large Gas Giant)
96 - 95,500 km - (large Gas Giant)
96.1 - 97,300 km - (large Gas Giant)
96.2 - 99,200 km - (large Gas Giant)
96.3 - 101,000 km - (large Gas Giant)
96.4 - 103,000 km - (large Gas Giant)
96.5 - 105,000 km - (large Gas Giant)
96.6 - 107,000 km - (large Gas Giant)
96.7 - 109,000 km - (large Gas Giant)
96.8 - 111,000 km - (large Gas Giant)
96.9 - 113,000 km - (large Gas Giant)
97 - 115,000 km - (large Gas Giant)
97.1 - 117,000 km - (large Gas Giant)
97.2 - 120,000 km - (large Gas Giant)
97.3 - 122,000 km - (large Gas Giant)
97.4 - 124,000 km - (large Gas Giant)
97.5 - 126,000 km - (large Gas Giant)
97.6 - 129,000 km - (large Gas Giant)
97.7 - 131,000 km - (large Gas Giant)
97.8 - 134,000 km - (large Gas Giant)
97.9 - 136,000 km - (large Gas Giant)
98 - 139,000 km - (large Gas Giant)
98.1 - 142,000 km - (large Gas Giant)
98.2 - 144,000 km - (large Gas Giant)
98.3 - 147,000 km - (large Gas Giant)
98.4 - 150,000 km - (large Gas Giant)
98.5 - 153,000 km - (large Gas Giant)
98.6 - 155,000 km - (large Gas Giant)
98.7 - 158,000 km - (large Gas Giant)
98.8 - 161,000 km - (large Gas Giant)
98.9 - 164,000 km - (large Gas Giant)
99 - 167,000 km - (large Gas Giant)
99.1 - 170,000 km - (large Gas Giant)
99.2 - 174,000 km - (large Gas Giant)
99.3 - 177,000 km - (large Gas Giant)
99.4 - 180,000 km - (large Gas Giant)
99.5 - 184,000 km - (large Gas Giant)
99.6 - 187,000 km - (large Gas Giant)
99.7 - 191,000 km - (large Gas Giant)
99.8 - 195,000 km - (large Gas Giant)
99.9 - 198,000 km - (large Gas Giant)

 

[Malenfant]

I have to ask, what's the advantage of this? Seems like a terribly cumbersome and complex way of getting numbers that people ordinarily just fudge.

 

[Space Cadet]

This system includes asteroids, comets, moons, planets, and gas giants all in one system. The table is complex, the way you roll for planet size is not, you simply roll d100 counting '00' as 0, or you can use your calculator's random function and get 3 significant digits of precision to generate tenths as in the above table. Leave anything smaller than a planet as an empty orbit, unless your generating satellites around a planet.

I have included 51 orbits in the chart of orbital distances above, and I will now generate the sizes of the planets in this example ignoring all results of less than 71.

orbit = Distance: index - size
00 = 7,500,000 km: 24.5
01 = 15,000,000 km: 63.8
02 = 22,400,000 km: 68.7
03 = 29,900,000 km: 80.8 - 5,550 km - (old Size 3)
04 = 37,400,000 km: 60.2
05 = 44,900,000 km: 85.4 - 13,100 km - (old Size 8)
06 = 52,300,000 km: 65.8
07 = 59,800,000 km: 14.3
08 = 71,000,000 km: 29.9
09 = 82,300,000 km: 89.7 - 29,400 km - (small Gas Giant)
10 = 93,500,000 km: 64.1
11 = 104,700,000 km: 76.2 - 2,260 km - (old Size 1)
12 = 115,900,000 km: 53.1
13 = 127,200,000 km: 22.7
14 = 138,400,000 km: 22.1
15 = 149,600,000 km: 08.9
16 = 172,000,000 km: 06.4
17 = 194,500,000 km: 47.7
18 = 216,900,000 km: 99.1 - 170,000 km - (large Gas Giant)
19 = 239,300,000 km: 80.8 - 5,550 km - (old Size 3)
20 = 284,200,000 km: 58.9
21 = 329,100,000 km: 55.5
22 = 374,000,000 km: 76.7 - 2,260 km - (old Size 1)
23 = 418,900,000 km: 64.1
24 = 508,700,000 km: 75.5 - 1,870 km - (old Size 1)
25 = 598,400,000 km: 36.9
26 = 688,200,000 km: 50.8
27 = 777,900,000 km: 69.9
28 = 957,400,000 km: 07.8
29 = 1,137,000,000 km: 81.6 - 6,450 km - (old Size 4)
30 = 1,316,000,000 km: 77.3 - 2,730 km - (old Size 2)
31 = 1,496,000,000 km: 77.9 - 2,730 km - (old Size 2)
32 = 1,855,000,000 km: 93.8 - 63,300 km - (small Gas Giant)
33 = 2,214,000,000 km: 58.6
34 = 2,573,000,000 km: 47.9
35 = 2,932,000,000 km: 03.6
36 = 3,650,000,000 km: 84.4 - 10,900 km - (old Size 7)
37 = 4,368,000,000 km: 42.6
38 = 5,086,000,000 km: 79.9 - 3,960 km - (old Size 2)
39 = 5,804,000,000 km: 39.9
40 = 7,240,000,000 km: 19.2
41 = 8,676,000,000 km: 43.3
42 = 10,110,000,000 km: 96.3 - 101,000 km - (large Gas Giant)
43 = 11,550,000,000 km: 16.0
44 = 14,420,000,000 km: 69.5
45 = 17,290,000,000 km: 99.0 - 167,000 km - (large Gas Giant)
46 = 20,170,000,000 km: 78.7 - 3,290 km - (old Size 2)
47 = 23,038,000,000 km: 11.7
48 = 28,780,000,000 km: 69.3
49 = 34,530,000,000 km: 94.4 - 70,800 km - (large Gas Giant)
50 = 40,270,000,000 km: 72.5 -
51 = 46,016,000,000 km: 1,070 km - (old Size 1)

Now we remove all extraneous orbits and renumber them showing only orbits with planets

orbit = Distance: index - size
1 = 29,900,000 km: 80.8 - 5,550 km - (old Size 3)
2 = 44,900,000 km: 85.4 - 13,100 km - (old Size 8)
3 = 82,300,000 km: 89.7 - 29,400 km - (small Gas Giant)
4 = 104,700,000 km: 76.2 - 2,260 km - (old Size 1)
5 = 216,900,000 km: 99.1 - 170,000 km - (large Gas Giant)
6 = 239,300,000 km: 80.8 - 5,550 km - (old Size 3)
7 = 374,000,000 km: 76.7 - 2,260 km - (old Size 1)
8 = 508,700,000 km: 75.5 - 1,870 km - (old Size 1)
9 = 1,137,000,000 km: 81.6 - 6,450 km - (old Size 4)
10 = 1,316,000,000 km: 77.3 - 2,730 km - (old Size 2)
11 = 1,496,000,000 km: 77.9 - 2,730 km - (old Size 2)
12 = 1,855,000,000 km: 93.8 - 63,300 km - (small Gas Giant)
13 = 3,650,000,000 km: 84.4 - 10,900 km - (old Size 7)
14 = 5,086,000,000 km: 79.9 - 3,960 km - (old Size 2)
15 = 10,110,000,000 km: 96.3 - 101,000 km - (large Gas Giant)
16 = 17,290,000,000 km: 99.0 - 167,000 km - (large Gas Giant)
17 = 20,170,000,000 km: 78.7 - 3,290 km - (old Size 2)
18 = 34,530,000,000 km: 94.4 - 70,800 km - (large Gas Giant)
19 = 40,270,000,000 km: 72.5 - 1,070 km - (old Size 1)
20 = 46,016,000,000 km: 1,070 km - (old Size 1)

 

[Space Cadet]

The advantage here is that the distances and sizes are more continuous, there is more randomness in the distribution of planets, and you have a better change of having two habitable planets in one system as they can be in very close orbits to one another and not restricted to Bode numbers.

 

[robject]

The level of detail is about as much as anyone would ever require, so to that extent your table is helpful.

There would probably need to be another "smoothing" function passed over the initial results, since (per your example) the world in orbit 6 is most likely orbiting around orbit 5 (the SGG). Similarly, the larger masses will probably affect things close to them by either capturing them or slinging them clear out of the system, isn't that right?

Also, at what point do the sizes become Asteroid Belts proper, or how do you differentiate between a very small asteroid and a member of a belt?

And, at what points does this system sync up with the game itself? How much value does this add compared with (1) effort, and (2) detail? Initially the effort looks reasonable, but if the orbits still have to be adjusted based on captures and ejections, then I wonder if there's some simplifying steps you could build in to anticipate this.

 

[robject]

Ah, and as for planet sizes; I think they would be just fine if simplified by a factor of 10. If need be, anyone can then generate an intermediate value; for instance, if a roll of 80 produces a world of diameter 4000km, then when someone wants more accuracy he can roll a d10 for the hundred's place. But I suspect many people won't care, and even fewer would bother with the 10s of km for a world of that size.

 

[robject]

Taking your gas giants as a further example: you've got GG's from 87 to 99. Surely 12 sizes of gas giant, from 16,000km to 190,000km, in regular intervals, is plenty? Then the enterprising referee can choose to refine the value by adding d10 x 10,000 km, or something?

 

[Space Cadet]

The scale is an exponent of 6.5. I've contrived this scale so that the largest gas giants are on the top. If I go further up this scale past 100, then your dealing with objects that have to be stars. Gas giants can't really get much bigger than the top of this scale, add more mass and they start to shrink again as they compress under their own weight, at a certain point you get back down to Jupiter sizes and the core of the planet starts to ignite turning it into a star. Nuclear reactions within the planets core allow for sizes larger than 99.9.

I used an exponential scale with the idea that there should be roughly an equal chance of having a terrestrial planet or a gas giant. If I simply rolled d100 and used the results to represent classic Traveller sizes, I'd get the same range, but most of the planets would be gas giants, about 90% of them.

The size indexes used serve not only to arrive at a value but to also store a size value in three simple digits. The Traveller Size digits serve a similar purpose. Instead of saying the planet has a diameter of 4,320 miles, you say its size four and remember that its approximately 4,000 miles in diameter, its a kind of data compression. using this table, you can store a whole bunch of planet sizes in 3 digits, so you basically substitute 3 digits for 1. Mainworlds range from 72.0 to 86.6, anything higher is a gas giant, and anything lower is too small to be a planet. The smallest gas giants are simply large terrestrial worlds that are so big, that they retain a thick atmosphere, so thick that the gases liquify under the intense pressure. maybe about a tenth of the plant's radius is atmosphere while the rest is a rocky mantle, and a liquid core surrounding a solid core made of iron. There is no way anyone can get down to the surface of the planet due to the think atmosphere, the atmosphere is completely opaque and so it is considered a gas giant. Small Gas giants tend to be denser than large ones.

 

[Space Cadet]

You might also interpret a result of between 50 and 63 to be an aseroid belt. Between 63 and 71 is a single large planetoid in its own orbit, and anything less than 50 is an empty orbit.

Gas giants grab the planet next in and next out as satellites if they are in adjacent orbit numbers. Terrestrial planets can coexist in orbits right next to each other without capturing the neighbor. I see no point in rolling up planets that are ejected from the star system. so we'll try this:

orbit = Distance: index - size
1 = 15,000,000 km: 63.8 - 198 km (small world)
2 = 22,400,000 km: 68.7 - 506 km (small World
3 = 29,900,000 km: 80.8 - 5,550 km - (old Size 3)
4 = 44,900,000 km: 85.4 - 13,100 km - (old Size 8)
- 60.2 - 113 km
- 65.8 - 288 km (small world)
5 = 82,300,000 km: 89.7 - 29,400 km - (small Gas Giant)
- 64.1 - 239 km (small world)
6 = 104,700,000 km: 76.2 - 2,260 km - (old Size 1)
7 = 115,900,000 km: 53.1 - 30.5 km (asteroid + belt)
8 = 216,900,000 km: 99.1 - 170,000 km - (large Gas Giant)
- 80.8 - 5,550 km - (old Size 3)
- 58.9 - 77.8 km (asteroid + belt)
9 = 329,100,000 km: 55.5 - 44.4 km (asteroid)
10 = 374,000,000 km: 76.7 - 2,260 km - (old Size 1)
11 = 508,700,000 km: 75.5 - 1,870 km - (old Size 1)
- 64.1 - 239 km (small world)
12 = 777,900,000 km: 69.9 - 610 km - (Small World)
13 = 1,137,000,000 km: 81.6 - 6,450 km - (old Size 4)
14 = 1,316,000,000 km: 77.3 - 2,730 km - (old Size 2)
15 = 1,855,000,000 km: 93.8 - 63,300 km - (small Gas Giant)
- 58.6 - 77.8 km (asteroid)
- 77.9 - 2,730 km - (old Size 2)
16 = 3,650,000,000 km: 84.4 - 10,900 km - (old Size 7)
17 = 5,086,000,000 km: 79.9 - 3,960 km - (old Size 2)
18 = 10,110,000,000 km: 96.3 - 101,000 km - (large Gas Giant)
19 = 17,290,000,000 km: 99.0 - 167,000 km - (large Gas Giant)
- 69.5 - 610 km (Small World)
- 78.7 - 3,290 km - (old Size 2)
20 = 34,530,000,000 km: 94.4 - 70,800 km - (large Gas Giant)
- 69.3 - 610 km (Small World)
- 72.5 - 1,070 km - (old Size 1)
- 1,070 km - (old Size 1)

 

[Malenfant]

Sorry, but I'm still not seeing what advantages this offers over the existing worldgen method - what's your rationale for coming up with this? There's nothing here that can't be done just by taking an existing radius and fudging some digits (ie. if you roll a size 8 world, then its radius is 6400 +/- 400 km. I can just say it's 6,274 km and be done with it, without having to roll on a huge table where world sizes are for some reason expressed in decimal points (I'm not clear why this is necessary either).

It also seems completely random and without any situational modifiers too, which is never a good thing when it comes to worldgen.

 

[Space Cadet]

World 8, the large gas giant is closer to the primary than Mars is to out Sun, if the star of this system is similar to our sun, then a good place to put the mainworld would be orbiting the large gas giant, since one of the satellites it captured is an asteroid - belt, then we'll interpret this as a ring system. This close to the star, the ring system is made up of rocky particles, not icy ones, the Moons orbiting this gas giant resemble Earth's moon, the small ones have mares or basaltic lava plains covering their nearsides while their far sides are more heavily cratered. The Main World would likely be the largest satellite orbiting this gas giant.
A random d100 roll gives a result of

82.1 - 7,080 km - (old Size 4), somewhat larger than Mars, the local gravity is about 1/2 Earth's gravity. Greater atmospheric optical depth due to the low gravity combined with a standard atmosphere enhances the greenhouse effect to give this satellite a temporate climate. The Moon has 89.5% hydrographics, mostly a series of achipelagos and islands of moderate size, it would make a great base for a frontier outpost, this system has alot of things that would keep a Belter happy. The Gas giant has alot of satellites besides the mainworld. The land life is imported Terran species, while the aquatic life is native to the planet. This system is quite a bit younger than the Terran System, no more than one billion years old, the central star is a G0 V class. There is an asteroid belt just beyond the Gas giant, the asteroids are far enough out so as to contain plenty of ices, volitiles and gases, as well as valuable ores. An intelligent aquatic race lives in the oceans of the mainworld, mostly they have little to do with the offworlders who reside on the islands of this moon.

 

[Space Cadet]

Originally posted by Malenfant:
Sorry, but I'm still not seeing what advantages this offers over the existing worldgen method - what's your rationale for coming up with this? There's nothing here that can't be done just by taking an existing radius and fudging some digits (ie. if you roll a size 8 world, then its radius is 6400 +/- 400 km. I can just say it's 6,274 km and be done with it, without having to roll on a huge table where world sizes are for some reason expressed in decimal points (I'm not clear why this is necessary either).

It also seems completely random and without any situational modifiers too, which is never a good thing when it comes to worldgen.

This system gives you a more specific size for the gas giants than simply listing them as large or small, this is important because the main world orbits a large gas giant which is the 8th planet from the star. The system gives a specific size for this gas giant, with this specific size, we have a better idea of how far out, 100 diameters from the gas giant is, this is how far from the gas giant a starship has to travel before making a jump, this gas giant also has alot of satellites, probably from 30 to 50 satellites including the mainworld, there is also a ring system, lots of places for pirates to hide, and starship have to travel quite a long distance from the planet to the jump point with alot of places to be ambushed from along the way in and out. Also the mainworld is tidally locked with the parent planet, the length of its day is the same as its orbital period around the gas giant, we have the size of the gas giant, now all we have to do is determine its density, and from that we can calculate its mass. Once we have its mass, and the Mainworld's distance from the planet, we can calculate its orbital period and hence its length of day.

 

[Scott Martin]

Originally posted by Space Cadet:
World 8, the large gas giant is closer to the primary than Mars is to out Sun, if the star of this system is similar to our sun, then a good place to put the mainworld would be orbiting the large gas giant, since one of the satellites it captured is an asteroid - belt<SNIP>

Wouldn't a GG at this range lose its hydrogen atmosphere? At which point it would no longer be a Gas Giant...

There is also the question as to whether you want to believe that Kepler's law will give discrete orbital distances at which bodies are possible (as seen in our solar system)

On the plus side, this syetem does lend itself to automated system generation, although you may want to figure out a mechanic for moons...

Scott Martin

 

[Malenfant]

This system gives you a more specific size for the gas giants than simply listing them as large or small, this is important because the main world orbits a large gas giant which is the 8th planet from the star.

Okay... but for that you could just have a separate 2d6-based table with columns for LGG or SGG and spare the complication of the arcane, meaningless decimal places and rolling 5d20 or d100 or whatever. You can call a planet a size 8, or you can call it a 85.3 or whatever, but 85.3 means nothing. "8" at least tells you it's 8 x 1000 miles in diameter.

It may be conceptually more elegant to have everything in one table, but in practical terms I don't think that any gains made by that can overcome the extra complication.

I think the biggest problem is that it's just too random though (I'll have a bit more time to go through it properly later tonight). There's no accounting for star type, for example. You've got gas giants mixed in with terrestrial planets with no rhyme or reason, no accounting for snow line at all either.

 

[Space Cadet]

The current evidence seems to suggest that gas giants may be found at any distance from the star. Also a d100 has a completely flat distribution, a 2d6 is weighted toward the midrange with 7s more likely than 2s or 12s. When one looks at our own Solar System, one sees 4 major planets and 4 gas giants, seems like equal chances for both. In our Solar System, the gas giants just happen to all be in the outer solar system and the rocky planets are closer to the Sun, now is that just coincidence, does it have something to do with how planets form, or is it the "observer effect", do life bearing planets require that all gas giants be in the outer solar system? There are probably many star systems that do not satisfy the requirements for the development of complex life forms.

5d20 is interesting, that produces alot of small planetoids, fewer terrestrial planets and few gas giants still. One system that I developed had many more orbital distances in the inner solar system than the outer solar system, you rolled 5d20 many times for the inner solar system and d100 for the outer solar system, this tends to produce more gas giants in the outer solar system, and makes terrestrial planets a greater percentage of those that appear in the inner solar system, this makes the result look more like out own Solar System.

Actually I can use an exponential table of distances for satellites around planets, using the same exponent of 6.5

distance = 6.5^(number/10)* 100 km
You get the following results

Orbt Distance
00 - 100 km
01 - 120 km
02 - 145 km
03 - 175 km
04 - 211 km
05 - 255 km
06 - 307 km
07 - 370 km
08 - 447 km
09 - 539 km
10 - 650 km
...

and the progression continues

50 - 1,160,000 km

These distances are the distances from the center of the planet, so naturally, some planet sizes will make some orbits unavailable as the planet occupy's the space.

 

[Malenfant]

That doesn't address the question though.

The current evidence seems to suggest that gas giants may be found at any distance from the star.

Gas giants can be found anywhere because of migration - migration isn't random, and it affects other planets closer in too. All your system does is place gas giants anywhere with no consideration for how they got there or how they affected anything else around them. Gas giants also disrupt or eject objects in nearby orbits (there are no stable orbits between about 4 AU and Jupiter's orbit for example. IIRC that is also because Saturn's there in a further orbit).

Our system isn't unique, it's quite possible that gas giants around other stars don't migrate much. But for most of them, the gas giants plow through the inner system and mix up all the planetesimals and eject a lot too. You can still get habitable planets if you have a hot jupiter that migrated in, but IIRC from the papers it should be very volatile-rich because of stuff dragged in by the gas giant from further out mixing in with the rocky stuff closer in. But that won't be possible every time.

Also a d100 has a completely flat distribution, a 2d6 is weighted toward the midrange with 7s more likely than 2s or 12s. When one looks at our own Solar System, one sees 4 major planets and 4 gas giants, seems like equal chances for both.

Simulations have indicated that you can have any number of rockies and quite a few jovians. The fact that we have four of each is meaningless really. The existing CT worldgen system may be based on 2d6, but there's also situational modifiers in there as well to offset that. Your system is just totally flat with no modifiers at all for circumstance.

Again, I can't see any advantage that using a very long table with meaningless numerical classifications offers over just using what we already have. It's certainly no more realistic to do it your way (in fact, it's less realistic because it's entirely random), and it's definitely not easier or as intuitive as what we have already.

BTW, your posting style is very familiar...

 

[Space Cadet]

I guess Secret Agent Border Reiver has clued you in. I think he has a spy program going on that tracks peoples e-mail accounts. Some day I'll have to get a new internet account so some folks can't tell who I am. I'd rather talk about what, not who, do you understand what I'm talking about? I'd just rather not let personalities get in the way of subject matter.

I understand that if we stay off the subject matter of politics, we should get along just fine, how about it, is that a deal?

There are some subject matters that are held close to the heart in which people will just not bend, it is useless to talk about such things, it is just a waste of time, you will not convince the other.

You have some good points about Solar System formation, its not random and yet it is. The molecules in a cloud of gas move randomly, yet they are governed by the laws of physics, gravity determines their direction of travel to some degree, and yet there is still alot of randomness in their motion. I'd think there would be something wrong with a die rolling system that produces nothing but 4 inner rocky planets and four outer gas giants. I don't think all planetary systems are limited to 8 major planets, I think it quite possible that some may have 20, and others may have 3.

As for relying on tables, you don't have to, the values derived on those tables all come from a specific mathematical equation. I don't even have to look at the table to come up with a value for any given number

79.3 for example plus into this equation

6.5^7.93 * 1.5 / 1,000 = 4,192.7 km or 4,190 km if you like it rounded off to 3 significant digits, go ahead, I didn't look at the table, check out that value to see if its correct.

If its just 79 then
6.5^7.9 * 1.5 / 1,000 = 3,963.75 or 3,960 rounded to three digits, as I don't think that part of the table has tenths.

One of the shortcomings of the traveller digit code is that it doesn't properly classify objects less than 200 km, or greater than 10,000 miles. I like one numerical system that deals with planets, gas giants, comets, asteroids, and stars. With three simple digits, you can classify a whole range of different objects of vastly differing sizes, that is the entire point of it. Whether my d100 system properly models star systems is another issue. Does it really matter, I could probably use the system I generated in a game or two. Few people both to model the whole solar system since formation anyway, I just want to get in a whole range of solar system objects that the traveller planetary codes don't classify. For example, if their is a space station orbiting a planet, the traveller codes don't indicate that. It could be that the mainworlds of some systems are actually space stations, rather than a proper planet. A Space Station could conceivably hold millions of people in comfort in an otherwise lifeless star system, they don't always have to be living under domes on a planet's surface, and my size system reaches down to space stations as well. A size 00 object is a ball of matter 1.5 meters in diameter for instance.

The code deals with planets from 1,000 miles to 10,000 miles

 

[Malenfant]

Well, politics is a no-go now - the politics board has been removed, anyone talking politics outside gets stomped on by the mods (which we now have, and are decent and timely in their response). So there won't be any talk of politics.

However, it will take more than a new email account to hide your true identity from people - your style just doesn't change at all, whether you're Tom Kalbfus, Laryssa, or Space Cadet. That and the fact that BR spotted you on another forum talking about the same thing, didn't exactly make it hard to figure out who you really were.

What worries me more here is that I know what your attitude to science and realism is. So long as you don't start claiming that science is wrong, or doesn't know anything about planetary formation, or anything like that then there won't be a problem.

Now, my main problem with this table isn't so much about realism, it's more about its necessity. I just don't think anyone ever needs to generate an entire continuum of objects from 1.5 metres in diameter up to 190,000km or whatever. If your stated aim is to come up with codes for objects that Traveller doesn't classify, then why not just add those to the existing system?

For example, Book 6 says that S (Small World) is 200km radius. Personally, I say it covers everything from 500 to 1500 km diameter (2d+3 x 100 km diameter). I also add a code T (Tiny) for things smaller than that, for which I use this table:

Roll (1d6) Size T Diameter

1: 4d6 km
2-3: 5d20 + 20 km
4-5: d% + 100 km (00 = 100)
6: (1d6 +3) x 50 km

You roll 1d6, then use the result to determine the length of each of the xyz axes of the object, because it's small enough to not have a spherical shape. That gives you a broad spectrum for all small bodies. Or, I just pick three numbers for each axis and be done with it.

For Jovians I just use a snowballing method (like 2300AD) to build them up from a smaller size.

 

[TheEngineer]

Hi !

Well, if I would have to describe a solar system a bit more detailed I would perhaps step away from using any codes for describing astrography at all.
Maybe just use the actual real worlds units like m,km, AU etc.
This is system independent, too

Anyway a exponential/logarithm style scale has its very charm, especially in an SF environment and is well used e.g. in TORG .....

Regards,

TE

 

[Liam Devlin]

How about a system that takes into account Star types/ age/ Sizes, and projects from there the amount of planetary bodies ejected from that? This conforms to the hard science that Mal & others in his field are working with now, rather than what we knew (or believed to have known) 20 years ago.

Say we look into generating the total possible number of bodies ejected by Type A, B, yellow G-Stars, F, K, & red M-class.

IIRC Mal had a post somewhere that each star had a finite amount of ejectionable mass--which correlated into planetary bodies (Gas Giants, Belts, Planets).

example: Say a Star ejected a mass with the simplified digit of 10. this could become 10x Size 1 planets, 5x Size 2 worlds, 1x Size 8 terran Sized world, and several others, and so on.

From these numbers of ejectable mass, perhaps then we can next extrapolate (in this possible order) Gas-giant bodies, planetoid belts, & Planets.

( Mal feel free to correct me if I'm off base here, but wouldn't this parallel/ conform to current science better? )

helpfully yours,