alt Hacker NewsSpaceEngine is also known for putting quite some effort into this; highly recommended: https://www.youtube.com/watch?v=_4TjdVAbXks
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I love the scale that FAQs for things like this provide, as well as the variety of questions.
Q: How many objects are there in SpaceEngine?
A: The entire Hipparcos catalog of stars, all known extrasolar planets, over ten thousand galaxies, most objects in the solar system, which adds up to 130,000 things. In addition, more galaxies and star systems than exist in reality in all of the observable universe.
Q: How can a water planet be hot?
A: Water in the upper atmosphere is in the form of hot vapor, but farther down it smoothly transitions into a liquid state under high pressure. Even deeper it turns into a solid state called ice VII.
Q: How do I move?
Use WASD keys.
It's fantastic software that's been around for many years, and has exquisite attention to detail on this and many other topics; this article also reminded me of it!
Wikipedia in one tab, and SpaceEngine in the other, is one of my favorite semi-educational gaming experiences. Great game. I haven't seen anything quite as nice even though it's quite long in the tooth.