I would like to thank divkeays for his previous post on moons Everything you need to know about Moons. However, it really wasn't, so I had substantial additions I wished to make so I have unstickied his post and stickied this in its place. If anyone has any additions or corrections to this post I will happily edit it.
How are moons useful?
1. Jump Gates can only be built on moons. JGs allow you to move your ships from one moon to another instantaneously and at zero fuel cost. Both the starting moon and the destination moon must have a JG.
Resources cannot be moved through JGs, so be sure you have enough fuel waiting at the destination moon to move your fleet.
To use a JG, select the moon from which you want to jump, click on Buildings > Jump Gate. You will now see a list of the ships on the moon similar to the Fleet screen and a drop down box from which you can select the destination moon. Select the ships you want to jump and the destination and then click Jump at the bottom.
After use, there is a cool down period before it can be used again. When you click on a particular JG, if it is cooling down you will see a real time countdown telling you how long before it can be used again. The drop down box will also show the cool down time of the other JGs, although this is static. If no cooldown time is indicated, that JG is ready for use.
The cooldown time is 60 min at level 1, 30 at level 2, 20 at level 3 etc. It can be expressed formulaicly as 60/n minutes where n is the level of the JG.
2. Sensor Phalanxes (Phalanx or lanx for short) can also only be built on moons. These can detect planet to planet movements of other players. This is useful if you want to attack another player.
To use a Phalanx, select the moon from which you want to do it. Each lanx attempt costs 5000 deuterium so there has to be enough deut on the selected moon. Hover your cursor over the target PLANET name or icon (moons cannot be lanxed) in the Galaxy screen and several options will appear. Click on Phalanx. A pop-up screen will appear. If there is no planet to planet activity it will say No Movement Detected. If there is activity you will see essentially an Overview screen showing what the owner of that planet himself would see on his own Overview screen, except you will NOT see any movement that has a moon on the other end.
3. That brings us to the third way moons are useful: any movement involving at least one moon as either the start or target or both cannot be lanxed, so your movements are invisible.
4. Related to invisibility, activity on a moon does not cause an activity * to appear. So if you restrict your activity to your moons you can hide the fact that you are online. This is essential if you want to do a ninja (which is when you reinforce a planet or moon that has an incoming attack so that you win the resulting battle).
How do I get a moon?
Moons can be created in two ways.
1. In any battle that results in a Debris Field (DF) there is a chance of a moon forming, proportional to the size of the DF. The maximum chance of this is 19%.
Players often give each Moon Shots (MS), which is a friendly attack specifically for the purpose of generating a chance at a moon. The exact number of ships required to generate a max 19% chance MS is 212 LC OR 53 BS OR 3726 EPs. Any combination of ships that results in the same or greater DF will also generate a 19% chance but those listed are the commonly used MS. 53 BS are the cheapest and faster than LC but they often destroy any sats on the planet and do damage to RLs. 3726 EPs is hard on the crystal but they are very fast and generally the preferred MS among higher ranked players. LC are a compromise. They are more expensive and slower than BS, but cheaper than EPs and like EPs they don't do any damage.
2. Moons can be bought with 200 Serios Rubies. Ruby moons are guaranteed to be at least 9700 km.
Great, I Have A Moon. Now What?
Once you have a moon, it will always start with only a single building field, so the first building you must build is a Lunar Base. Each level of LB gives you a net 4 extra fields (technically it gives you 5 but the LB itself uses 1).
The next buildings are probably Robot Factory level 1, 2 and 3. Each level of Robot Factory reduces the build time of other buildings, but it reduces it differently than a planetary Robot Factory. On a moon, it reduces the current build time by 1/(n+1) where n is the level of the Factory.
Then Lunar Base 2. In this second round you may want to increase the Factory again, and build a Jump Gate and ACS Depot. Then Lunar Base 3. Then you can start building a Sensor Phalanx.
Moons do not produce resources so do not build Storage.
Additional Notes
1. The moon is not formed from the DF. The same amount of DF appears regardless of whether a moon forms or not.
Q: If the moon doesn't form from the DF, what does it form from?
A: The immense energy of the cataclysm causes a moon to form from quantum fluctuations ex nihilo of course!
2. Moons can be destroyed by RIPs. Moon vary in size up to 9999 km. Ruby moons are guaranteed to be at least 9700 km. The larger the moon, the more RIPs are required to destroy it.