Each system contains a random (yet predetermined) number and type of planets and moons (or occasionally very large asteroids). To study a new world you may spend 0.1 turn scanning it to receive basic information, if you spend 0.5 turn scanning it, you may be able to pick details or small things you might have missed otherwise (such as crashed ships, ruins, invisible hazards, etc). Upon entering a system you will receive the types and locations of each planet within that system (example; you'd know right away if a planet was a volcanic world or not).
Each world has 3 stats; Ore, Gas and Fertility. Ore and Gas represent the resources the planet has available, these are used for building structures, ships and various other things and having high resources is always good. Fertility is the third stat, it represents how habitable the world is, worlds have a starting infrastructure cap of twice a world's fertility. This means it is easier to colonize worlds with higher fertility.
Worlds are listed according to their distance from their star. There are 5 positions; simply labeled 1,2,3,4 and 5. Planets closer to the star have higher ore and lower gas stats, whereas those further away have the opposite and planets that are near the middle of a system usually have higher fertility (these stats will already be adjusted when you scan them). Note that some planets also have moons, these will be labeled as such. For example, if there is a system in hex 26-26 and there is a world in the third position that has a moon, the location of the planet (when posting, and listing your structures, etc) is 26-26.3.1 (first numbers show the hex, second shows the position and third shows the planet), whereas the moon would be represented by 26-188.8.131.52 (note if there are multiple moons they will be labeled as other numbers, .2, .3, etc). Sometimes there is more than 1 planet within the same position. In this case the position is the same but the planet's number is different, for example; if you had two worlds in that same system in the third position their coords would be: 26-26.3.1 and 26-26.3.2. This all sounds more complicated than it really is, if you have any questions just ask.
Many worlds possess hazards, some worse than others. Hazards can affect colonization and exploration of such worlds. Other worlds simply have unusual qualities such as high gravity or simply being very small.
Tech caches and artifacts
Worlds have a small chance of possessing caches of technology. It could be in the form of a crashed ship, ancient ruins, wreckage from a battle, etc. You can also stumble across valuable and powerful alien artifacts. Some caches are easy to find while others will often be unnoticed by a casual glance.
If you look at the galaxy map you will note there are various types of terrain. Asteroid fields, nebulae, etc. These have a substantial effect on ships and worlds;
Wormholes appear randomly and may disappear just as suddenly, traversing them is always dangerous. Ships without 8+ sensor value and 4+ warp value suffer a strength 6 energy damage hit. Ships attempting to use a wormhole without warp suffer a strength 12 energy damage hit. The wormhole itself forms a gateway between two random locations, travel takes 0.1 turn.
Left by a race long since gone, these immobile rings can be used by those with warp to launch themselves to other gates. Until you have coordinates for multiple gateways, you will jump blindly towards a random gate. Movement for using the gates is 3 hexes/warp value, this travel ignores all terrain and cannot be stopped before arriving at the other gate.