There are many celestial bodies throughout the galaxy. By far the most common are planets, usually between 4x4 and 20x20 in size, and which are categorised by the type of atmosphere (toxic, breathable and absent/none) and climate (hot, temperate and cold). There is an additional category to the various combinations of the above, 'gas giant', which covers both the atmosphere and the climate.

There also exist a multitude of asteroids, comets and moons. Asteroids and comets are only ever 1x1 in size, but the largest of moons may reach 3x3 and rival small planets in size. Of course, given the sheer size of the galaxy, and the phenomena and histories throughout, there do exist exceptions to these general rules.

Finally, there are the suns, invariably 30x30, on which nothing can survive.

The images you will see while ascending/descending to/from atmosphere on the various bodies are available by clicking on the images below.

Hot no Atmosphere	Hot toxic Atmosphere	Hot breathable	Temperate breathable
Cold breathable	Cold toxic Atmosphere	Cold no Atmosphere	Gas Giant
Sun	Moon	Asteroid Field	Comet
Black Hole	Temperate toxic Atmosphere

Each planet is a grid of various terrains. Using Tatooine as an example, we see that the planet on the left is composed of many terrain grids (right map).

Each planet is assigned a grid that will act as a map. The grid size varies based on the size of the planet. The smallest planet has a 5x5 grid, the largest a 20x20 grid. All grids are square, that means that the lengths of the x and y sides of the grid will always be the same.

Each grid square is assigned a topographical description from this list:

	Black Hole Terrain		Cave		Crater		Desert
	Forest		Gas Giant		Glacier		Grassland
	Jungle		Mountain		Ocean		River
	Rock		Sun Terrain		Swamp		Volcanic

Each square of the planetary map is also considered a grid. These grids squares are considered the terrains of the Combine.

Each terrain exists in two versions. One is a natural version, where you can move, and a city version, where you may build facilities.

In order to transform a natural terrain into a city, you must pay a minimum 1,500,000 credits.
In order to build a facility in a city, you must either own the city, ask the permission of the city owner, or if the city is a NPC city, you may build without permission.

List of terrains that can be travelled on (click on a terrain to see the full version):

Cave

Crater

Desert

Forest

Gas Giant

Glacier

Grassland

Jungle

Mountain

Ocean

River

Rock

Swamp

Volcanic

Each Terrain type has a percentage of you finding a raw material deposit on it. It is more likely to find a raw material deposit on certain types of terrain. For more information on what raw materials can be found on each terrain, look at Mining

List of Terrains and their percentages:

Black Hole Terrain	0%
Cave	10%
Crater	8%
Desert	5%
Forest	3%
Gas Giant	3%
Glacier	1%
Grassland	2%
Jungle	4%
Mountain	10%
Ocean	2%
River	4%
Rock	8%
Sun Terrain	0%
Swamp	4%
Volcanic	0%

Each Terrain type has a percentage of you finding a creature on it. It is more likely to find creatures on certain types of terrain. For more information on what creatures can be found on each terrain, look at Creatures

List of Terrains and their percentages:

Black Hole Terrain	0%
Cave	4%
Crater	1%
Desert	3%
Forest	15%
Gas Giant	1%
Glacier	1%
Grassland	12%
Jungle	10%
Mountain	4%
Ocean	9%
River	5%
Rock	2%
Sun Terrain	0%
Swamp	7%
Volcanic	1%