Pluto's orbit overlaps Neptune's, does this mean Pluto will hit Neptune sometime?

  • We know that the orbits of Pluto and Neptune overlap.
    This means that pluto sometimes crosses the orbit of Neptune; will Pluto hit Neptune in any circumstance?


    The accepted answer is incorrect. NJ's answer is correct.

    @user931 And why would the accepted answer be incorrect? Especially given the extra information in the comments to the accepted answer...

  • Dieudonné

    Dieudonné Correct answer

    8 years ago

    No, Pluto is a so called resonant trans-neptunian object; the orbital period of Pluto is almost exactly 3:2 (1.5) times that of Neptune. This means that every time Pluto nears perihelion and is therefore closest to the Sun and also closest to the orbit of Neptune, Neptune is always at a specific angle (50° according to Wikipedia) in front or behind Pluto.
    (See for instance Figure 3 and surrounding text in Jewitt, D., Morbidelli, A., & Rauer, H. (2007). Trans-Neptunian Objects and Comets. Springer.)


    Furthermore, the orbits do not actually overlap. Remember that the Solar System is 3-dimensional. Pluto's orbit is substantially tilted relative to Neptune's, and even if they weren't resonant they wouldn't collide because their orbits don't intersect at any point. (Looking at a map of the Solar System from "above", at the two points where the orbits seem to intersect they're at different "heights".)

    Quite true, but the fact that it is resonant prevents even perturbations from Neptune, which could cause it to collide with Neptune or (more likely) being ejected from the solar system. That is the reason why there are so many more bodies at resonant orbits than at non-resonant orbits.

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