Planets provide you with the resources and research required to construct, upgrade, and maintain your fleet. There are 5 different kinds of
planet environments which provide bonuses for different resources. The exception is the Paradise planet which gives bonuses to all 4 resources.
A blue Ocean Planet
Gives research facility bonus
A brown Arid desert planet
Gives energy plant bonus
A green planet with various terrains
Gives residential facility bonus
A violet planet composed with various materials, such as carbon
Gives mining facility bonus
A rare planet with extremely good environment.
Gives a bonus to all buildings
+Research, Energy, Gold and Mineral income
There are 5 ranks of planets D through S which affect the max level and resource bonuses which you can obtain. Once again Paradise is an exception with only ranks B through S.