Our solar system just got a little bit bigger.
Researchers have uncovered evidence of two more planets circling our sun far beyond Pluto's orbit. It's a discovery that scientists say could revolutionize current models on the formation of the solar system.
The discovery came from a new comprehensive new analysis of the orbits of "extreme trans-Neptunian objects" by researchers at the University of Cambridge and Complutense University of Madrid.
"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.
Though few newly discovered bodies have been as large as Pluto, some of these distant trans-Neptunian objects have enough mass to be considered planets: In 2005, astronomer Mike Brown and his team announced the discovery of Eris, a TNO barely larger than Pluto. A NASA Jet Propulsion Laboratory press release described the object as the "10th planet." Both Pluto and Eris were exiled from elementary school solar systems in 2006, downgraded to the status of "dwarf planets."
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.
This doesn't mean a expedition to our solar system's brand new dwarf planets is out of the question: After a nine-year journey, NASA's New Horizons spacecraft kicked off its approach to Pluto on Thursday.
h/t NBC News