Have you ever seen a movie, where a spaceship accidentally gets a fracture, a hole in the hull, and then all of a sudden the air from the inside, maybe along with screaming passengers and stuff, is "sucked" or ejected into the open space with a tremendous power. Well, not exactly sucked, it's because of the vacuum, but you know how it works.
Now, my question is: if all that vast space around the Earth is the empty vacuum, why the Earth's atmosphere does not get "sucked" off? You might say it's because of gravity, but gravity is not that powerful compared with the "force" of vacuum. E.g., you can easily jump up off the Earth, temporary overcoming the gravity at least for a few inches and then landing, but could you jump from the hole in the spaceship hull? Not a chance. Meanwhile, the air pressure and gravity force in the spaceship and on Earth is not very different, you can survive in both. So, where's the secret? What keeps the Earth's atmosphere from escaping from Earth?