Searching for X in all the Wrong Places?

Back in 2012 astronomers noticed that the orbits of several Kuyper Belt objects seemed to be influenced by a gravitationally powerful body. Oh, wow, what did this mean? Is there a massive planet somewhere inside or beyond the Kuyper Belt, whose influence is manifested by these objects’ orbits?

The name planet X (not the Roman numeral) is being applied yet again. Planet X has a long, storied history.

Even before the name planet X came into existence, many astronomers were speculating on the existence of a trans-Neptunian planet, maybe two. You see, the orbit of Uranus was being perturbed, by more than the mass of Neptune could account for. Starting in the mid-1800’s, numerous hypotheses were published that supposedly explained the orbit of Uranus, only to fall short when observational evidence could not confirm them. Then came Percival Lowell, you know, of Mars’ canal fame. In 1906, Lowell coined the name planet X and began searching for it at his Lowell observatory in Flagstaff, AZ. Lowell Died in 1916, not having found planet X and the search was put on hold.

In 1929, the new director of Lowell Observatory, Vesto Slipher, revived the planet X search by assigning the project to a newly hired farm kid named Clyde Tombaugh. In less than a year Tombaugh found planet X, subsequently named Pluto. That was that, eh? Not so fast, there still was the issue of Uranus’s orbit. Over the years, Pluto’s mass was determined – 1/500 of Earth’s mass.  Pluto could not account for the mass needed to affect Uranus. Pluto was not planet X.  Now what?

Well, continue the search! As technology improved, the hypotheses became ever more complex. Bigger and more capable telescopes were used. Yet, no planet X. Then came a confounding discovery.

Several other objects like Pluto, but smaller, were discovered in the Kuyper belt and that was fine, until the orbit of Kyper Belt object Sedna was determined. Sedna has a very eccentric orbit, taking it past the inner edge of the Kuyper Belt (Neptune’s orbit), then close to the outer edge. That’s many, many billions of miles! In 2012, Further investigations showed that some other Kuyper Belt objects also have eccentric orbits. The conclusion was that a massive object somewhere inside or just beyond the Kuyper Belt was influencing their orbits. Otherwise they should be elliptical. Again, several hypotheses grew from the data and searches commenced. Well, no planet X has been found yet.

Recently, a new hypothesis has been published – why not? Yukun Huang, from the University of British Columbia, presented his research findings at the 55th meeting of the American Astronomical Society. Huang took a different approach. He ran a computer simulation of the known orbits of objects – backwards! The simulation indicated these objects had an encounter with a massive object, but 4 billion years ago! After further research, Huang calculated that the event was instigated by a primordial planet, perhaps only 100 million years old. This planet was subsequently ejected from the solar system, so…it’s not there! Or, is it?

What’s in the Sky?

January 8; before sunrise; south-southeast: A thin waning crescent Moon gets tight with Antares, the alpha star in Scorpius, Venus to the upper left. For an added treat look high in the southwest at 06:08:30 and watch as the ISS comes out of Earth’s shadow about 10 seconds later, heading southeast.