>>13554519I would start with working to understand gravity.
>helps keep the core moltenGravity from the moon causes tides on earth, in the surface water as well as in the core. By stretching and flexing the core, it keeps it hot, just through friction with itself.
>magnetic field aliveBy keeping that molten metal moving, it prevents the core from cooling down and also from the heavier elements from settling into the inner core as quickly. Think of it like stirring. The fact that there is all this movement and churning is part of what makes our magnetic field so strong, as compared to venus or Mars, whose cores are both older (since the theia impact imparted shit loads of matter and energy to earth) and without a large moon to prevent their core from settling as quickly.
>retain our atmosphereSo on Mars, gravity is so weak that it's atompshere (though probably about as dense as earth's was now) was stripped away by solar radiation (an endless stream of photons and gamma particles pushing the highest and least dense gaseous particles off). On venus, however, the gravity is about what earth's is, and it kept all of its gaseous atmosphere in a dense layer that is taking much longer to be stripped away by solar radiation. On earth, though, when Theia impacted, a ton of our native atmosphere was blown out into space, and most of that collected as oxides and other minerals on the moon as it formed from the chunks of debris and gaseous spray. Thus, earth has a less dense atmosphere than venus by quite a margin, but far dense than Mars, whereas if we were not impacted by theia, we would probably be as hot, high-pressure and dead as venus is.
Hope that's a good starting point. Lemme know if you want to know anything else.
