Our solar system just got a little bit bigger.
"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," lead author Carlos de la Fuente Marcos said in a statement.
The researchers studied 13 TNOs, dwarf planets like Pluto and Sedna that travel around the sun at great distances in elliptical orbits. Their results are detailed in two papers in the journal Monthly Notices of the Royal Astronomical Society Letters.
"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 TNOs, and we consider that the most probable explanation is that other unknown planets exist beyond Neptune and Pluto," Marcos said..
Scientists have discovered hundreds of TNOs, most a of which are part of the Kuiper belt, a swarm of icy bodies left over from the solar system's formation that orbit near the ecliptic plane beyond Neptune.
The potential undiscovered worlds discussed by Cambridge and Complutense scientists "would be more massive than Earth," researchers said, and would lie so far away that they'd be extremely difficult to locate with current scientific instruments.
h/t NBC News