Io is the closest moon of Jupiter, its almost the exact same size as our own moon but with the interesting effect of it being one of the most violent places in our solar system. Reason behind it is that because three of Jupiter's moons (including Io) line up periodically, with the moon being between both the two other moons and Jupiter its self, it quite literally distorts by about 100 meters; as a result the kinetic energy heats up the small moon to the point there is constant eruptions happening. It's one of the most fascinating places in our solar system.
This piece overall gave me hell. It was almost abandoned a couple of times but I've came to a result where I'm okay to let it go. All Photoshop over about 12 hours (way too long)