In the earlier builds there were some moons orbiting around the planet you played on. Haven't seen them for a few builds - is this part of implementing the broader solar system structure?
Moons do not appear on custom planets, I don't think. Only on randomly generated ones. Uber is currently getting interplanetary up and running (slowly but surely), so there is no real point in adding that extra bit of geometry to render.
Mushroom is correct. As we're in the process of bringing multiple planets online, it's not actually an issue with extra geometry, but more that we simply don't allow you to build multi-planet systems yet. That may come online even before you can play on multiple planets, but they'll be pretty close to each other in terms of release.
I wish moons had features other than craters. But until they do I don't see any point in including them in custom planet. There is nothing to customize about them unless you really like a specific array of craters.
Thanks guys, I didn't notice the connection between the custom vs random ones having moons. Seeing the moon 'set' behind the planet you're on is fantastic. Seeing the sun set is great too - I'm sure it'll be mind blowing once some post processing, lens flare etc ends up in there