World Building is something that every author has to do, no matter what the genre or setting. For example, here’s a passage from Laura Lippman’s In Big Trouble, followed by another from And here’s another one from Robert Silverberg’s Lord Valentine’s Castle:
A sign hangs next to the cradle of Texas liberty, reminding visitors that concealed firearms are not permit-ted on the grounds…
…Within the walls, it’s like being in a shallow dish— azure sky above, the taller buildings crowded around, dwarfing the Spanish mission, which isn’t very big to begin with. She walks through the gardens, noting the placement of each plant, each bench, each sign. Changeis not to be tolerated. She picks up a cup with a lit-tle electric blue raspa juice inside and drops it in the trash, as fastidious in her own way as the Alamo’s keepers, the Daughters of the Republic of Texas.
It is a shrine, and not only to Texas liberty. A shrine to her, to them.
And then after walking all day through a golden haze of humid warmth that gathered around him like fine wetfleece, Valentine came to a great ridge of outcroppingwhite stone overlooking the city of Pidruid. It was the provincial capital, sprawling and splendid, the biggest city he had come upon since—since?—the biggest in a long while of wandering in any case.
There he halted, finding a seat at the edge of the soft, crumbling white ridge, digging his booted feet into the flaking ragged stone, and he sat there star- ing down at Pidruid, blinking as though newly out of sleep. On this summer day, twilight was still some
hours away, and the sun hung high to the southwest
beyond Pidruid, out over the Great Sea. I will rest
here for a while, Valentine thought, and then I will
go down into Pidruid and find lodging for the night.
The Lippman establishes the setting as contemporary San Antonio, downtown to be specific. The Silverberg is a science fiction secondary world, but both have the same effect: introducing and drawing us into a living, breathing setting we can picture in our minds. This is world building.
No matter what your genre or setting, the basic concerns tend to be the same. Some require a bit more than others, like science fiction worlds requiring space travel, alien cultures, other planets, etc. but all still call for thoughtful consideration of the same categories of details. In her chapbook Checking on Culture, Lee Killough offers a great checklist which lists the relevant concerns. Here’s my adaptation of it:
Use this list by checking off the items as you go through them and think through that aspect of your world. But first things first, before you start world building, you must already know your time frame. Near future, current day, or far future? When does your story take place and where? This will determine everything else. Then your research and planning can center around things relevant to that time period. Once we know the time frame, we proceed on with the list. The order depends on your priorities, but for me, it usually goes something like this:
Existing or Secondary World
He returned his attention to Barbirike Sea, which stretched, long and slender as a spear, for fifty miles
or so through the valley below the gray cliff on which
Kasinibon’s fortress-like retreat was perched. Long
rows of tall sharp-tipped crescent dunes, soft as
clouds from this distance, bordered its shores. They
too were red. Even the air here had a red reflected
shimmer. The sun itself seemed to have taken on a
tinge of it. Kasinibon had explained yesterday, thoughFurvain had not been particularly interested in hear- ing it at the time, that the Sea of Barbirike was hometo untold billions of tiny crustaceans whose fragile
brightcolored shells, decomposing over the millennia, had imparted that bloody hue to the sea’s waters and
given rise also to the red sands of the adjacent dunes.
Furvain wondered whether his royal father, who had
such an obsessive interest in intense color effects,
had ever made the journey out here to see this place. Surely he had. Surely.
(The Book of Changes, Robert Silverberg)
Existing worlds are Earth or known planets in our solar system or even a few beyond. Secondary are inventions of the author. Are you inventing everything or building on what already exists and what we already know? Then you need to know geography, gravity, culture of lifeforms, etc. How many suns or moons? How many other planets? Etc.
If you are creating a secondary world, do not put your planet around a famous celestial body just because it is well known. Many of these are highly unlikely to have habitable planets around them and it requires careful thought about viability before placing planets there, particularly earth-like, human habituated ones. You should carefully consider the scientific realities of planetary location and solar system building before deciding upon such a course, even if writing a soft science story, instead of hard science fiction. Because believability for readers is paramount. Remember: you should create the questions readers ask carefully and guide them toward questions you can answer satisfactorily and away from ones you cannot. Not one covers everything. There will always be gaps. But try to avoid awkwardly obvious, glaring ones. Also, constellations will appear differently from various points around the galaxy, so don’t describe them as they appear on Earth when viewed from elsewhere.
Secondary or not, ask yourself what are the key geographic features and how do they effect population density, location of settlements, travel around and across the surface, economics, weather, etc.? Avoid oversimplifying but just saying a planet is all jungle, all ice, etc. because based on location from sun, rotation, geography and other factors, this is not scientifically plausible as we know it and will tend to seem unrealistic and poorly considered. Frank Herbert put a lot of thought into his desert Dune planet, but too often the results of oversimplifying come across as lazy thinking. Planets are big places and will have a lot of variety. For example, civilizations will form cities around bodies of drinking water and food supplies, and their diets will vary depending upon the area in which they live and the wildlife, plants, etc. that also reside there. Those things also choose habitats based upon location of resources and so on and so forth. There is a circle and a chain of logic that will determine much of it and thus should be considered.
Geography determines travel options. Heavily mountainous areas may not have room for landing zones for starships or local air travel. Large bodies of water may need to be traversed via boats, ships or other craft in order to avoid long delays in supply, commerce, shipping, etc. So consider these things in determining where your cities are located and how people get between them.
Gravity affects quality of life from retention of water and atmosphere to breathing to ability to run and jump, etc. But this can also affect the magnetic field and exposure to radiation from solar flares, cosmic rays, and more. High gravity worlds would have shorter mountains and require people to have thicker, stronger muscles. Air would be denser and tension on body parts might lead to premature aging, sagging faces, etc. Also accidents might multiply as objects are thrown about or pulled loose by stronger gravity and strike people, vehicles, buildings, lifeforms, etc. On high gravity worlds, rain and rivers would erode land much more quickly as well, smoothing rough edges. Oceans would be calmer and bigger, more extensive, and evaporation would be slower, leaving the air and atmosphere drier with water taking longer to boil and clouds hanging lower. Planes would need bigger wings as well. Reverse these factors for lower gravity worlds, with larger land masses and smaller bodies of water, etc.
If your planet has an Earthlike atmosphere, a very slow day will result in extremes of temperature from day to night. Wind speeds will be affected by rotation as well. Oblation will tend to occur for planets with shorter days and rotations verses longer. It will be thicker or thinner at the equator accordingly. Axial tilt will determine the seasons. Slants greater than Earth will create more extreme seasons. Weather conditions will be affected. The amount of exposure to the sun’s heat determines extremes. Wind and ocean currents will moderate the effects. Higher rotation planets will have more hurricanes and dangerous winds. Ice caps form because poles receive less heat and water freezes. Planets with ice caps will generally be cooler than those without. The skin color of people can be affected by location with desert peoples generally tending toward darker tones due to sun exposure, while people living in shadows or colder climates who spend much time underground, indoors, etc. may have lighter skin. All of these are interesting factors to take into account.
As you can see there are many factors to consider and I can only scratch the surface here. You may not use all the details but knowing them gives you the option to write the story you need to tell, without being boxed in or slowed down by ignorance.