Astronomers Say There Are Two Unknown Planets in Our Solar System

Astronomers at the Complutense University of Madrid (UCM) and the University of Cambridge say their calculations indicate there are at least two unknown planets in our solar system located well beyond the dwarf planet Pluto. One of these planets could be a dark and icy super-Earth, up to ten times larger than Earth.

The astronomers say there are two trans-Plutonian planets waiting to be discovered. The researchers argue that these planets must exist in order to explain the orbital behavior of extreme trans-Neptunian objects (ETNO). The astronomers say these objects should be distributed randomly and have characteristics such as a semi-major axis with a value close to 150 AU, an inclination of almost 0 degrees and an angle of perihelion also close to 0 degrees or 180 degrees. However, the observed characteristics of the objects include values of the semi-major axis between 150 AU and 525 AU. The researchers say the average inclination of their orbit is about 20 degrees and the argument of Perihelion is -31 degrees.

Carlos de la Fuente Marcos, scientist at the UCM and co-author of the study, says in a statement, "This excess of objects with unexpected orbital parameters makes us believe that some invisible forces are altering the distribution of the orbital elements of the ETNO and we consider that the most probable explanation is that other unknown planets exist beyond Neptune and Pluto. The exact number is uncertain, given that the data that we have is limited, but our calculations suggest that there are at least two planets, and probably more, within the confines of our solar system."

The researchers note a couple of recent discoveries indicate planets can form farther away from their planet star than previously thought, such as the planet-forming disk found over 100 astronomical units from the star HL Tauri.

The Universe Today has an image here that shows some of the largest known trans-Neptunian objects (TNOs). Two research papers the astronomers published about additional unknown planets can be found here and here.

Image: NASA/JPL-Caltech

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