## Probabilities in the Galaxy A Distribution Model for habitable Planets Copyright © Klaus Piontzik

 German Version

## 2.4 - Approximately earth-great Planets

 Approximately earth-great planets are planets about the size of the earth with at least one earth mass. Almost all planets of approximately the size of the earth found so far lie in a range of 1.3 to 4.8 earth masses. Most of these planets are slightly larger than Earth, or at most twice as large.

According to the "Habitable Exoplanets Catalog" of September 2015, 10 of 31 habitable planets are about the size of the earth. This corresponds to a share of 32.258 %. The probability factor is Fg = 0.322,58 = 10:31.

According to the "Habitable Exoplanets Catalog" of December 2017, 22 out of 53 habitable planets are about the size of the earth. This corresponds to a share of 41.509 %. The probability factor is Fg = 0.415,094 = 22:53.

iIf you calculate the mean value from both information, you get:

 Fgm = 0.368,837 ± 0.046 Fgm = 1,212:3,286
 2.4.1 Theorem 36.883% of all habitable planets, in sun-like star systems, are probably approximately earth-great.

Then, from equation 1.6.1 for solar-like star systems that have habitable planets, a relationship can also be extrapolated for approximately earth-greatplanets.

Related to all star systems A in our galaxy, the number
Nhg of solar-like star systems, with habitable, approximately earth-great planets, results to:

 2.4.2 Equation Nhg = Nh · Fg Nhg= A · Fsph · Fg Nhg= A · Fs · Fp · Fh · Fg

Starting point are 100-300 billion solar systems in the galaxy. Insert into equation 2.4.2:

 2.4.3 Theorem There could be 2.458 to 7.376 million, approximately earth-great, habitable planets in solar-like star systems, in the galaxy.

The probability for habitable planets, about the size of the earth, in solar-like star systems, in the galaxy, is then:

 2.4.4 Definition Fhg = Fsph · Fg

Fhg = Fsph·Fg
Fhg= 1:15,000 · 1,212:3,286
Fhg= 0.000,024,589 = 1:40,668

Among about 40,668 sun-like star systems there is one, with at least one habitable, approximately earth-great planet.

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