I have a bit of intuition on microscopic structures, so I "easily" understand things such as chemistry, nuclear and particle physics and the such. I'm no expert in these subject or anything but I do have a easier time learning it. But I REALLY have a hard time understanding some macroscopical/astronomical structures. But I intend to fix it. Anyways, what I still don't understand about gravity is the circular/elliptical orbits of planets/satellites/stars/etc. This question might sound silly but... Why don't the moon just falls on Earth? I understand it is constantly "falling" towards the Earth and all. What I mean is, why does it have a horizontal component of velocity which makes it "not really fall"? Is it because it had a initial velocity different than zero? Does it depends on the initial conditions of the system or something like that?