THE SOUTHWORTH PLANETARIUM
207-780-4249      www.usm.maine.edu/planet
70 Falmouth Street     Portland, Maine 04103
43.6667° N                   70.2667° W
Founded January 1970
Julian date:  2457757.16

            "Mind walkers"

THE DAILY ASTRONOMER
Thursday, January 5, 2017

Planet Ten

Yes, probably.

That was an answer to your question, "Is there a Planet Ten?"

Although we're legally required to tell innocent children that our solar system contains only eight planets (Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune), we all know that it also has a ninth planet (Pluto).    Now, it is quite possible that the solar system harbors a tenth planet, far out in its darkest, coldest and most forsaken regions.   It is estimated to be ten times more massive and have a radius four times larger than Earth.  With an average distance seven hundred times greater than the distance separating Earth from the Sun, its orbital period could be 10,000 - 20,000 Earth years.  

The problem is: nobody has yet observed this world.and some astronomers are still not convinced its exists.    Nevertheless, many other astronomers are engaged in an earnest pursuit to locate this hypothetical planet.     One must wonder: if nobody has seen this planet, how can astronomers estimate its mass, size, and measures its orbital period?   They based these estimations on their observations of bodies they have observed, such as the recently discovered trans-Neptunian object Sedna and five other bodies orbiting beyond Neptune.       These objects have developed similar orbital characteristics that suggests the presence of a more massive body far beyond them.   Simply put, these bodies have exhibited perturbations that cannot be explained by the gravitational influence of  known bodies. 

​A possible orbital path.     According to some models, Planet Ten is now lurking within the dark regions just west of Orion.   Those markings indicate its possible position during a two thousand year period.   

As a body's gravitational influence depends on its mass and its distance from affected particles,  an unseen planet's mass, size and distance can be inferred from the perturbations, albeit with wider error margins that one would have with a celestial body one can directly observe.

If an astronomer does find this world, it will most likely be designated a planet by the International Astronomical Union.  In 2006, the IAU adopted a new definition of a planet.   A planet must now be spherical, have established a stable orbit around the Sun and also must have cleared it region of debris.   Something as massive as this hypothetical world is believed to be would have to be spherical.   A sufficiently massive body will mold itself through gravity into a spherical shape.    It will also be massive enough to have drawn all proximate bodies into itself.      

We might be adding a tenth member to our planetary family.     Well, we won't be adding the member.  It's been out there for quite awhile. However, if we see it, we'll know it exists...until the philosophers hear about it.