A new salvo has been fired in the back-and-forth debate about the existence of Planet Nine.
In 2014, astronomers Scott Sheppard and Chadwick Trujillo suggested that a giant unseen “perturber” may lurk in the far outer solar system. The duo based this hypothesis on peculiarities in the orbits of the dwarf planet Sedna, the newfound object 2012 VP113 and several other bodies beyond the orbit of Neptune (trans-Neptunian objects, or TNOs).
The case grew in January 2016, when astronomers Konstantin Batygin and Mike Brown found evidence that the orbits of additional TNOs had been sculpted. Batygin and Brown dubbed the hypothetical perturber “Planet Nine” and calculated that, if the world exists, it’s likely about 10 times more massive than Earth and lies perhaps 600 astronomical units (AU) from the sun. (One AU is the average Earth-sun distance — about 93 million miles, or 150 million kilometers.) [The Evidence for ‘Planet Nine’ in Our Solar System (Gallery)]
Then, last summer, Sheppard and Trujillo found two new TNOs that Planet Nine may have tugged on, increasing the number of possibly affected bodies yet again.
But a team of researchers with the Outer Solar System Origins Survey (OSSOS) project recently cast doubt on the strength of all this evidence. The apparent “clustering” seen in the TNO orbits could simply result from observational biases, the OSSOS team reported in a paper that has been accepted for publication in The Astronomical Journal.
And that’s where the most recent salvo comes in. (But keep in mind that the above paragraphs provide an incomplete recounting; there have been many Planet Nine studies published over the past 18 months.) Two astronomers from the Complutense University of Madrid in Spain studied 22 “extreme” TNOs (ETNOs), which orbit the sun at an average distance of at least 150 AU and never get closer than Neptune. (Neptune lies about 30 AU from the sun and orbits on a roughly…