Scientists ponder the existence of theoretical new planet in the solar system

May 20, 2012 – SPACE – An as yet undiscovered planet might be orbiting at the dark fringes of the solar system, according to new research. Too far out to be easily spotted by telescopes, the potential unseen planet appears to be making its presence felt by disturbing the orbits of so-called Kuiper belt objects, said Rodney Gomes, an astronomer at the National Observatory of Brazil in Rio de Janeiro. Kuiper belt objects are small icy bodies—including some dwarf planets—that lie beyond the orbit of Neptune. Once considered the ninth planet in our system, the dwarf planet Pluto, for example, is one of the largest Kuiper belt objects, at about 1,400 miles (2,300 kilometers) wide. Dozens of the other objects are hundreds of miles across, and more are being discovered every year. How big exactly the planetary body might be isn’t clear, but there are a lot of possibilities, Gomes added. Based on his calculations, Gomes thinks a Neptune-size world, about four times bigger than Earth, orbiting 140 billion miles (225 billion kilometers) away from the sun—about 1,500 times farther than Earth—would do the trick. But so would a Mars-size object—roughly half Earth’s size—in a highly elongated orbit that would occasionally bring the body sweeping to within 5 billion miles (8 billion kilometers) of the sun. Gomes speculates that the mystery object could be a rogue planet that was kicked out of its own star system and later captured by the sun’s gravity. Or the putative planet could have formed closer to our sun, only to be cast outward by gravitational encounters with other planets. However, actually finding such a world would be a challenge. To begin with, the planet might be pretty dim. Also, Gomes’s simulations don’t give astronomers any clue as to where to point their telescopes—“it can be anywhere,” he said. “Obviously, finding another planet in the solar system is a big deal,” said Rory Barnes, an astronomer at the University of Washington. But, he added, “I don’t think he really has any evidence that suggests it is out there.” Douglas Hamilton, an astronomer from the University of Maryland, agrees that the new findings are far from definitive. “What he showed in his probability arguments is that it’s slightly more likely. He doesn’t have a smoking gun yet.” –National Geographic

I discuss the scenario for lost and acquired planets in the solar system in my new book, The 7th Protocol