The galaxy is filled with worlds. Worlds your players want to go explore... and murder people and steal everything, because gamers. But still. If you're looking to make a lot of worlds for your Starfinder game, you'll want the Galaxy Exploration Manual. Paizo takes a look inside it in this preview.
From the article:
The Starfinder Galaxy Exploration Manual offers a robust, yet simple system for generating entire science fantasy worlds on the fly, including populating them with creatures, adventures, and more. So let’s make ourselves a world, starting with nothing but our trusty dice and the two-page Building Worlds article in the Galaxy Exploration Manual.
For our first step, we’ll see what type of world we’re generating: is it a gas giant, an asteroid—even a colony ship? We roll 42 on our d% table and get… a terrestrial world, which is one that’s naturally habitable and has one or more biomes (coming in step 3). Not a bad place to start for most worlds, though we could always just choose something weirder if we wanted it.
Next, we’ll see what kind of gravity and atmosphere this world has by rolling d% twice more. Results of 42 and 84 give us standard gravity and a thick atmosphere, respectively. Handy page references guide us to the parts of the Starfinder Core Rulebook that’ll tell us more about thick atmospheres.
Next comes a key step: identifying our world’s biomes! What kinds of environments are present on this world? Do the creatures and cultures reside entirely in the air? In rugged mountains or soggy marshes? Let’s roll a d12 on the biomes table and find out! Our first roll is a 2, which gives us the aquatic biome. We could stop there and have a water world, but let’s roll a couple more times and see what else we get. Two more rolls (a 5 and a 10) add forest and subterranean biomes to the mix.