Ninth planet may have been discovered

It is not everyday that we get to hear that a new planet may have been discovered within our solar system. Apart from the planets that are the visible to the naked eye, only two other planets have ever been discovered; both these discoveries were made well before the beginning of the twentieth century.

A new paper authored by Caltech scientists Konstanin Batygin and Michael Brown was published in The Astronomical Journal, yesterday. The authors claim that they may have discovered the ninth planet of our solar system using theoretical simulations. They base their hypothesis on the motion of family of trans-Neptunian objects at the outer edge of our solar system which move in odd orbits around the sun. The authors explain this peculiar behavior by theorizing that a new planet, currently called Planet Nine, might be nudging these trans-Neptunian objects into their odd orbits. If this planet exists then it must have an orbital period of 15,000 years and is seven times farther than Neptune is to the sun.

This is not the first time a planet has been theorized to exist based on its gravitational influence on other objects in the solar system. In the mid nineteenth century, when astronomers observed the orbit of Uranus, it did not follow Newton's equations of motion. They could explain this behavior only if they assumed that there was another massive planet beyond the orbit of Uranus that tugged on Uranus. When astronomers searched for this planet, they found Neptune. This almost happened once again when the orbit of Neptune was observed to deviate from Newton's equation and could not be explained by the known planets at the time. Emboldened by their success from the previous time astronomers commenced the search for Planet X. After a couple of decades, Clyde Tombaugh discovered Pluto. Though, initially, it was thought to be Planet X, it later became clear that Pluto was way too small to have a significant effect on Neptune's orbit. Astronomers also realized that there was an error in the calculation of the orbit of Neptune, correcting which, there was no longer a need for Planet X to account for the deviation in the orbit of Neptune. Similarly, the orbit of Mercury traced a strange path causing its perihelion to precess. Astronomers assumed that an unseen planet named Vulcan orbited within the orbit of Mercury causing it to deviate from Newton's equations of motion. Later, Einstein's General theory of relativity explained this behavior, eliminating the need for Vulcan.

I haven't gone into the details about the orbit of the new planet as there are several wonderful sources already available, that cover this topic in great detail

• Astronomers say a Neptune-sized planet lurks beyond Pluto by Eric Hand on Science


• Evidence grows for giant planet on fringes of Solar System by Alexandra Witze on Nature


• Scientists Find Evidence for Ninth Planet in Solar System by Nadia Drake on National Geographic


• Ninth Planet May Exist Beyond Pluto, Scientists Report by Kenneth Chang on The New York Times

If a new planet is discovered, it is definitely a Nobel worthy discovery. Based on their calculations, the authors of the paper have also predicted the approximate position of this planet, which will help in the search for the planet. But they believe that it might take up to 5 years before they can know with certainty.

It is interesting that Michael Brown may have discovered the ninth planet of our solar system considering he is one of the astronomers responsible for the demotion of Pluto, with his discovery of the dwarf planet Eris. He also goes by the name Pluto killer on twitter.