while (True):
    vp.rate(500)
    
 	#Calculte the force using gravitationalForce function
    star.force = gravitationalForce(star,planet1)+gravitationalForce(star,planet2)+gravitationalForce(star,planet3)
    planet1.force = gravitationalForce(planet1,star)+gravitationalForce(planet1,planet2)+gravitationalForce(planet1,planet3)
    planet2.force = gravitationalForce(planet2,star)+gravitationalForce(planet2,planet1)+gravitationalForce(planet2,planet3)
    planet3.force = gravitationalForce(planet3,star)+gravitationalForce(planet3,planet1)+gravitationalForce(planet3,planet2)

    #Update momentum, position and time
    star.momentum = star.momentum + star.force*dt
    planet1.momentum = planet1.momentum + planet1.force*dt
    planet2.momentum = planet2.momentum + planet2.force*dt
    planet3.momentum = planet3.momentum + planet3.force*dt

    star.pos = star.pos + star.momentum/star.mass*dt
    planet1.pos = planet1.pos + planet1.momentum/planet1.mass*dt
    planet2.pos = planet2.pos + planet2.momentum/planet2.mass*dt
    planet3.pos = planet3.pos + planet3.momentum/planet3.mass*dt
    
    t += dt