The force of gravity determines the trajectories of the celestial bodies. Mathematical analysis reveals that there are three types of trajectories possible for a body moving in a gravitational field determined by Newton’s law of gravity.
- If one of the bodies has very high speed relative to the other the moving body traces out a hyperbola. The equation for this is
x 2/a2 – y 2/b2 =1
- If the speeds of the bodies are beelow a certain threshold value they move in an elliptical curve. x 2/a2 + y 2/b2 =1
- The limiting case between the hyperbola and the ellipse is the parabola. y=ax2
Those geometrical objects can be illustrated by slicing the cone according to the figure above.