Astronomers can't see "Planet Nine." But it makes its presence known.
The massive hypothetical object, which supposedly looms at the edge of our solar system, has been invoked to explain the strange clustering of objects in the Kuiper belt and the unusual way they orbit the Sun.
Now Planet Nine predictors Konstantin Batygin and Mike Brown of Caltech, along with graduate student Elizabeth Bailey, offer another piece of evidence for the elusive sphere's existence: It adds "wobble" to the solar system, they say, tilting it in relation to the sun.
"Because Planet Nine is so massive and has an orbit tilted compared to the other planets, the solar...