“Force fields are directional. The gravitational field is a force field and forces are directional. In the case of gravity, the direction of the force is toward the object that created the field. What, you may then ask, happens when there are several gravitational fields set up by several objects? For example, the gravitational field at the surface of the earth also contains component fields arising from the moon and the sun. The answer is that the various fields combine to give a net gravitational field, but they don't add numerically; each field has its own direction, and the directions must be taken into account. Thus there is a point between the earth and the moon where the two gravitational fields, being in opposite directions, cancel each other out. When a moon rocket is fired, it must have enough power to reach that point or else it will fall back to the earth. Beyond that point it will be pulled toward the moon. This compounding of forces also causes the tides as the water in oceans and seas is pulled toward the sun and moon. Even though those tugs are imperceptible to us, they create a variety of tides, such as neap and ebb tides, depending on the positions of the sun and moon.”