Analogous to the previous Special Basic Model we can generalize the equations 3.1.1 and 3.3.4 for habitable "Earths 2" in sun-like systems so that they apply to general star systems with habitable, earth-like planets:

The number of N_hexGal of all star systems with habitable, earth-like planets in the galaxy is then the sum of all spectral classes:

Assuming that the other star systems, i.e. not sun-like stars, also have the same or similar planetary distribution, it is possible to estimate how many systems with habitable "Earths 2" could exist.

The number N_hexGal of all star systems with habitable, earth-like planets in the galaxy (∑ F_x = 1), is approximately equivalent to:

Inserting all values (F_e = 0.1) into equation 8.3.4:

N_hexGal1 = (100-300)·10⁹ · 1:4200 · 1:69
N_hexGal1 = 345,065 – 1,035,196 habitable „Earth 2“

Inserting all values (F_e = 0,01) into equation 8.3.4:

N_hexGal2 = (100-300)·10⁹ · 1:4200 · 1:691
N_hexGal2 = 34,456 – 103,370 habitable „Earth 2“

The two results can then be summarized to the following statement::

The probability for habitable, earth-like planets in any star system, in the galaxy, is then:
:

F_hexGal = F_ph · F_gae
F_hexGal = 1:4200 · (1:69–1:691)
F_hexGal = 1:289,800 – 1: 2,902,200

Only every 289,800 - 2,902,200th star system produces an earth-like planet, in the habitable zone.


It is left to the reader for practice to make the calculations for planets with life and intelligence himself. Otherwise, see the table at the end of the book (page 137).