Click the flag. Pluto makes two orbits for every three orbits of Neptune around the Sun. The ratio of their frequencies is 3 to 2, a kind of "orbital resonance." To bring out the analogy between the orbital frequencies and musical frequencies (once called the music of the spheres), when Pluto is directly below Sun it plays note E. When Neptune is directly below Sun we hear note B, a "perfect fifth" about E. B has 3/2 the frequency of E, just as the orbital ratio is 3/2. You can adjust "speed" but the ratios of the angular frequencies remains 3 to 2. Sizes and distances are not to scale.
Focusing on orbital frequency ratios by illustrating relative angular frequency (or "angular velocity"). I set Neptune to orbit 1.5 times as fast as Pluto. Color is distance between the 2 planets.
