In the new paper, Kat Volk and Renu Malhotra of the University of Arizona's Lunar and Planetary Laboratory (LPL), show that this new planet has given away its presence only by controlling the orbital planes of a population of space rocks known as Kuiper Belt Objects, or KBOs, in the icy outskirts of the solar system. While most KBOs orbit the Sun with orbital tilts that average out to what astronomers call the invariable plane of the solar system, the most distant of the KBOs do not. If one were to think of the average orbital plane of objects in the outer solar system as a sheet, it should be quite flat past 50 AU. But going further out from 50 to 80 AU, they found that the average plane actually warps away from the invariable plane. So something unknown is warping that plane.
According to their calculations, something at least as massive as Mars would be needed to cause such a warp. The most likely place a planetary mass object could be hiding would be in the galactic plane, an area so densely packed with stars that telescopic surveys tend to avoid it.
Our chance to catch a glimpse of ‘Planet Ten’ might come fairly soon, however, once construction of the Large Synoptic Survey Telescope is completed. The LSST will bring the number of observed KBOs from the current number of about 2000 up to 40,000. The big new telescope will cover the sky much more comprehensively than previous surveys and it should be able to detect Planet Ten.
Source: University of Arizona
The curiously warped mean plane of the Kuiper belt" - Kathryn Volk, Renu Malhotra - Astrophysical Journal - June 2017 - arXiv:1704.02444
Credit for image featured at top of page: A planetary mass object the size of Mars would be sufficient to produce the observed perturbations in the distant Kuiper Belt. Credit: Heather Roper/LPL