But what keeps these celestial bodies from falling from the sky? Well, gravity of course! Anything that has mass also has gravity. Because gravity is proportional to mass, if the mass were to increase, so would its gravity. For this reason the gravity that a person generates is much weaker than the gravity generated by a planet. Gravity is only felt if something is working against it from the outside. For example, when you stand on Earth, the Earth's gravity pulls you down. The ground however pushes you back up with a force that is equally strong. When you stand however you feel as though your head and body is pushed into your feet. This is your weight! Therefore your weight is actually how much force is exerted as the ground pushes you up. Your mass is what is contained in your entire body. This is why in space astronauts may be weightless, but he/ she will still have the same amount of mass.
People do not fall from the Earth because of the force of gravity between the people and the Earth. Anything that has a mass attracts each other with a force of gravity that increases as its mass increases and decreases when the centers of the masses are further away from each other. No matter where you stand on Earth, gravity always pulls you to the center. You may not feel it when you float in space even though the gravity from Earth still pulls at you because there is not anything such as the ground to work against gravity. For example, when you jump up you feel weightless for a moment because the reaction of the Earth is not pushing you back up.