[system_generation] Frequency / Type of planets

[TangentFoxy]

From Why We Haven't Found Any Earthlike Planets:

• Earth-like planets were defined to have a radius 0.9 < R⨂ < 1.2 and a semi-major axis 0.8 AU < a < 1.2 AU. Only G-type stars are considered with this definition.
  • 2.7% of G-type stars should have an earthlike planet (and 6.36% of all stars should have an earthlike planet by the above definition).