In 1930, astronomer Clyde Tombaugh discovered the fabled "Ninth Planet" (or "Planet X"), while working at theLowell Observatory in Arizona. The existence of this body had been predicted before.
After receiving more than 1,000 suggestions from around the world, and a debate among the Observatory's staff, this newfound object was named Pluto.
Since that time, Pluto has been the subject of a lot of study, a naming controversy, and was visited for the first time on July 14th, 2015.
One thing that has been clear from the beginning is the eccentric nature of the dwarf planet. According to new research, Pluto is stable over longer timescales, but is subject to chaotic perturbance and changes over shorter timescales.
The research was done by Renu Malhotra, the Louise Foucar Marshall Science Research Professor at the University of Arizona.
The paper about their findings was published in the Proceedings of the National Academy of Sciences.
The difference between the planets and Pluto is that the planets follow a nearly circular path around the Sun close to its equator.
It takes a long time for the dwarf planet to complete a single orbit around the Sun and follow a highly elliptical plane.
The eccentric nature of its orbit means that it takes 20 years for it to get closer to the Sun than it does Neptune.
Astronomers became aware of the mystery of the nature of the dwarf planet after it was discovered. Since then, multiple efforts have been made to recreate the past and future of its elliptical path, which has revealed a surprising property that protects it from colliding with Neptune.
The mean motion resonance is the orbital resonance condition, according to Malhotra.
The condition ensures that at the time that Neptune is at the same heliocentric distance as Pluto, its longitude is nearly 90 degrees away. There is a different type of orbital resonance known as the "vZLK oscillation", which is why Pluto comes to perihelion at a location well above the plane of Neptune's orbit.
The phenomenon was studied by von Zeipel, Lidov, and Kozai as part of the three-body problem.
The problem consists of taking the initial positions and velocities of three massive objects and solving for their subsequent motion according to the theory of universal gravity.
In the late 1980's, with the availability of more powerful computers, numerical simulations showed that small deviations of initial conditions lead to exponential divergence of the orbital.
This chaos is limited. It has been found in numerical simulations that the two special properties of Pluto's orbit persist over gigayear timescales, making it remarkably stable despite the chaos indicators.
For their study, Malhotra and Ito conducted numerical simulations of the future of the Solar System.
They wanted to address unresolved questions about the peculiar orbits of the dwarf planet. planet migration theory is one of the questions addressed by research conducted over the past few decades.
During the Solar System's early history, Neptune pulled Pluto into its current mean motion resonance.
A major prediction of this theory is that other Trans-Neptunian objects would share the same resonance condition.
The more widespread acceptance of planet migration theory is a result of this discovery.
The vZLK oscillation is closely linked toPluto's orbital inclination. We reasoned that if we could understand better the conditions for the vZLK oscillation, we could solve the mystery of its inclination. We started by looking at the role of the other giant planets on the path of Pluto.
To do this, they ran computer simulations that included eight different combinations of giant planet perturbation. These N-body simulations had interactions.
All three of the giant planets were needed to recover the vZLK.
There are 21 parameters needed to represent the forces of Jupiter, Saturn, and Uranus on Pluto. This is a large space to explore.
To simplify these calculations, Malhotra and Ito introduced some simplifications. This included representing each planet with a circular ring of uniform density, a total mass equal to the planet's, and a ring radius equal to the planet's average distance from the Sun.
The effect of Jupiter, Saturn, and Uranus (J2), which was equivalent to the effect of an Observer Sun, was represented by a single parameter.
There is a narrow range in the J2 parameters in which the vZLK oscillation is possible, thanks to a fortuitous arrangement of the mass and orbits of the giant planets.
The result indicates that the conditions for Trans-Neptunian objects changed during the planet migration era in the Solar System. It is likely that the inclination of Pluto began during this evolution.
Future studies of the outer Solar System are likely to be affected by these results.
Astronomers will learn more about the migration history of the giant planets and how they eventually settled into their current orbits with further study, according to Malhotra. It could lead to the discovery of a novel mechanism that will explain the origin of high orbital inclinations.
This will be useful for the study of Solar System dynamics. Researchers in this field were starting to suspect that the chaotic nature of the orbital mechanics might have erased evidence that might shed light on the evolution of the dwarf planet.
I think that our work raises new hope for making a connection between present-day Solar System dynamics and historical Solar System dynamics. There is a major unsolved problem regarding the origin of the orbital inclinations of minor planets throughout the solar system.
The value of simple(r) approximations for a complicated problem is one of the points that our study underscores.
The article was published by Universe Today. The original article is worth a read.
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