No, 2009 MS9 is not a planet. It is a minor planet or asteroid.
Prograde and retrograde refer to the direction of an object's orbit around a larger body. Prograde means the object orbits in the same direction as the body's rotation, while retrograde means the object orbits in the opposite direction.
The best way to determine if 2009 MS9 is prograde or retrograde is to look at its orbital direction in relation to the direction of the Sun's rotation. If it is moving in the same direction, it is prograde. If it is moving in the opposite direction, it is retrograde.
The main factor that determines the direction of an object's orbit is the initial angular momentum of the object when it formed. Other factors that can influence an object's orbit include gravitational interactions with other objects and collisions.
Yes, the direction of an object's orbit can have implications for its stability and potential for collisions with other objects. Objects with retrograde orbits are more likely to collide with other objects, while objects with prograde orbits are generally more stable.