Abstract: This paper is the theory of existence of two planets in long time ago between the orbits of Mars and Jupiter. As it is shown here the planets rate of change of their angular velocity in the orbits circulating around Sun is between two numbers less than one. Although this number is not an exact number but Jupiter’s number is out of this domain. Also when we look at the distances of the planets from Sun, we see a big gap of orbital distance between Mars and Jupiter. For explanation of such irregularity of distances and also angular velocity, especially for planet of Jupiter, Two rates of changes are introduced here. First is the rate of change of distances for planets and the second is the rate of change of angular velocities for them. By calculating those average values and comparison with the values for planet of Jupiter, we could conclude the possibility that could had existed not one, but two planets between Mars and Jupiter. Perhaps by asteroids collisions and then by gravity of Jupiter they have been destructed. Now, there exists Asteroids Belt between the orbits of Mars and Jupiter. The paper explains this possibility of existence of such planets and their approximate distances from the sun and their orbital angular velocities that they could have had. By calculation mentioned in this paper the approximate medium orbit distance of the first planet (X1) from sun could had been: and its average angular velocity: For the second planet (X2), the approximate medium orbit distance from sun could had been: and its average angular velocity: .Abstract: This paper is the theory of existence of two planets in long time ago between the orbits of Mars and Jupiter. As it is shown here the planets rate of change of their angular velocity in the orbits circulating around Sun is between two numbers less than one. Although this number is not an exact number but Jupiter’s number is out of this domain. Also...Show More