In so many Trek episodes they land on "oxygen/nitrogen planets", usually with lush vegetation (and often with very human-like inhabitants, even though many sport latex and putty facial features). And inhabitants conveniently speak modern English (sometimes explained by the "universal translator").
We are "finding" so many planets, quite a few that seem to be in an "inhabitable zone". I say "find", because we can't actually see other planets, we detect them by their periodic occlusion of their stars. Each eclipse dips a star's light output. Diffraction prevents us from seeing them; we couldn't even see Pluto until a fly-by --- the lens diameter to see features on Pluto from Earth would have to be thousands of miles wide. Imagine how big of a lens it would take to see planets around other stars!
https://phys.libretexts.org/Bookshe...ction/4.06:_Circular_Apertures_and_Resolution
Free oxygen on a planet indicates life; it is not a stable material, left to its own it would degrade to oxides. On Earth the greatest oxygen generator is phytoplankton (converting CO2). So "Class M" by definition indicates a working biosphere. There are billions of stars, in billions of galaxies (but most are diffuse), and billions and billions of planets.
So how many "Class M" planets do you think there are, where actors ...I-I-I mean explorers can walk around blissfully without a space suit?
Wouldn't it be fun to book a weekend at a resort on Risa, with several moons lighting a sparkling tropical beach?
What are the odds?
We are "finding" so many planets, quite a few that seem to be in an "inhabitable zone". I say "find", because we can't actually see other planets, we detect them by their periodic occlusion of their stars. Each eclipse dips a star's light output. Diffraction prevents us from seeing them; we couldn't even see Pluto until a fly-by --- the lens diameter to see features on Pluto from Earth would have to be thousands of miles wide. Imagine how big of a lens it would take to see planets around other stars!
https://phys.libretexts.org/Bookshe...ction/4.06:_Circular_Apertures_and_Resolution
Free oxygen on a planet indicates life; it is not a stable material, left to its own it would degrade to oxides. On Earth the greatest oxygen generator is phytoplankton (converting CO2). So "Class M" by definition indicates a working biosphere. There are billions of stars, in billions of galaxies (but most are diffuse), and billions and billions of planets.
So how many "Class M" planets do you think there are, where actors ...I-I-I mean explorers can walk around blissfully without a space suit?
Wouldn't it be fun to book a weekend at a resort on Risa, with several moons lighting a sparkling tropical beach?
What are the odds?