Will the temperature be different on the day or night side of moons and planets, and how will temperature change when spaceship doors are open if the environment's and the spaceship's temperatures are very different?

Okay, so first things first: right now it will not be different. That's something that we're working on regarding the time of day change. The other aspects will be based off the room system. So when the spaceship opens, assuming there's not a bulkhead or airlock associated with it, it will be vented and it will take on the larger room, which is basically the planet. And so, therefore, your temperature will drop instantly. But those are being worked on now, so they're not in 3.9.