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

 German Version

## 2.6 - Approximately earth-like Planets

 Among the approximately earth-great planets there are still a number of planets which have a mass of earth about the size of the earth and which have a certain similarity to the earth in the orbit time around their central star, as well as in the rotation time. Such planets are referred to here as approximately earth-like planets.

According to the "Habitable Exoplanets Catalog" of September 2015, 4 out of 10 habitable planets about the size of the earth can be described as distant earth-like.
This corresponds to a share of 40 %. The probability factor is F
a = 0.4 = 2:5.

According to the "Habitable Exoplanets Catalog" of December 2017, 5 of 13 selected habitable planets about the size of the Earth can be described as distant earth-like.
This corresponds to a share of 38.4 %. The probability factor is F
a = 0.384,615 = 5:13.

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

 Fgm = 0.392,307 ± 0.007 Fgm = 51:130
 2.6.1 Theorem 39.23 % of all habitable planets, in sun-like star systems, are probably approximately earth-like.

hen equation 2.4.2 can be used to extrapolate a relationship for approximately earth-like planets
Related to all star systems A in our galaxy, the number N
ha of the solar-like star systems, with habitable, approximately earth-like planets, results to:

 2.6.2 Equation Nha = Nhg · Fa Nha= A · Fsph · Fg · Fa Nha= A · Fs · Fp · Fh · Fg · Fa

Starting point are 100-300 billion solar systems, in the galaxy, and inserting into equation 2.5.2 provides:

 2.6.3 Theorem There could be between 0.964 and 2.893 million approximately earth-like habitable planets in solar-like star systems, in our galaxy.

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

 2.6.4 Definition Fha = Fhg · Fa Fha= Fsph · Fg · Fa Fha= Fs · Fp · Fh · Fg · Fa

Fha = Fsph·Fg·Fa
Fha= 1:15,000 · 1,212:3,286 · 51:130
Fha= 1:103,664

As a result, only about every 103,664th sun-like star system produces a approximately earth-like planet in the habitable zone.

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