When a small mass is placed near a massive mass, they attract each other with equal and opposite forces. This force is too small to move the massive body noticeably, but the small body is pulled by the force towards the massive body.
The path the small body follows is called a field line or line of force.
The gravitational field strength is equal to force per unit mass.
g=F/m
Field patterns
Gravitational fields can be uniform or radial.
At extremely long distances to the body, the field lines are spread all over the object towards its centre. A small body will be pulled towards the centre of the body regardless of position. These fields can be considered radial.
At shorter distances (such as on the surface of the Earth), gravitational fields are uniform, because at such a short distance the gravitational field strength is the same in direction and magnitude throughout the field. Uniform field lines are parallel.
