Life on Planets
A habitable-zone planet is a place where life is possible. A living world is a place where it exists, and a lander is what tells the two apart.
Two similar words
A habitable-zone planet is a place where life is possible; anyone who has opened the system can see it. A living world is a place where life exists; that is known to whoever landed a probe there and to everyone who comes after.
A planet with the right temperature is only a promise. The news begins when something lands on it and takes a look.
There is a third question too — whether a person could live there. The air answers it; see "Air and People".
What a world can grow
The generator derives life from the planet itself: from its star's light, its gravity, water, tides and surface. So a biosphere reads as a consequence of this particular world, and what grows under a dim star is nothing like what grows under a bright one. On a light planet trunks reach higher, held up by the weak gravity.
Sometimes — far more rarely — someone down there is thinking.
The lander
To learn what is on a planet, you have to put something down on it. A lander is a ship's order: the copy stands over a habitable-zone planet and carries a scanner in its hull. The lander is free: living worlds usually lie where you have no warehouse yet.
It answers in layers: is there life, is there a mind, who are they. The whole report fits into about a quarter of an hour. A dead planet ends at the first layer: it has nothing more to tell.
The lander is easy to confuse with the probe flight. The lander reads life on its own, in game time. In a probe flight you steer the probe over the terrain and survey resources — see "Probe Flight".
The probe stays, the ship is free
Once it has landed, you can leave the same hour. The layers arrive on their own, in the notifications and in the "Life" register.
What has been read is a fact of the world: whoever reaches the system second sees what your probe discovered and won't land one of their own. A world is discovered once, and the mark of it stays on the hull of the copy that found it.
No life at home
The starting system holds no living worlds — ever. You will have to fly to your first living world, and the search for life becomes a real expedition. Which was rather the point.
What a find gives you
You can't talk to what you find, and there are no points for finding it. A discovered mind gives you knowledge of the world, a mark on the hull of the copy that found it and a reason to tell your neighbour about it over the radio. When you think about it, that is quite a lot.