A planet is a celestial body orbiting a star. Your homeworld is your main planet. When you first start the game, your homeworld will be the first planet you receive. Every planet not owned by another player allows a user to form a colony on that planet. A player can have up to 9 planets by establishing colonies. You may change your homeworld by abandoning it if you have a colony.
Temperature affects how much energy is gained from Helios Solar Satellites and how much hydrogen is created from Hydrogen Refineries. The closer a planet is to spot 1, the hotter it will generally be and thus the more energy it will gain from Helios Solar Satellites. The further away a planet is from spot 1, the colder it will typically be which means more hydrogen from Hydrogen Refineries.
Fields are the amount of space a planet has to build upon and are used every time a building is constructed or upgraded. You can continue building and upgrade on any planet until you have used up all fields. If all fields on a planet are filled you cannot continue building unless you teardown already constructed buildings or Terraform the planet. Defenses do not use up an field slots on a planet.
Your home world always starts with 163 fields, but colonies get a random number. Planet sizes are first determined using a normal distribution, based on a mean and standard deviation (see table), which are both determined by what planet slot is being colonized. If the Gaussian random number generator returns a value outside of 1 standard deviation away from the mean in either direction (which occurs roughly 32% of the time) a uniformly distributed random number between 40 and 320 is used instead. No planet larger than 320 or smaller than 40 may exist.
|Planet Slot||Mean Size||Standard Deviation||Lower Limit*||Upper Limit*|
*All planets have roughly a 32% chance of having a random number in the interval 40 to 320 fields instead of the usual method of mean and standard deviation.
A player can abandon any of their planets, including their homeworld. You cannot abandon your homeworld unless you have at least one other colony established. When a planet is abandoned all resources on the surface, all buildings, and any ships in orbit are lost. Therefore, before abandoning a planet, deploy all of your ships and remaining resources, including droids, to one of your other planets. A planet cannot be abandoned while a transport, deployment, or attack is underway from it. This is to avoid game errors by recalling a transport to an empty planet.
To abandon a planet, select it as the active planet and go to the planet's home screen, then click the "Abandon This Planet" button. For safety sake you must then type ABANDON in all caps and click the abandon button. The planet, everything on it, and everything orbiting it, will be lost. Research will not be lost as it is not associated with any particular planet.