奇闻：太阳系还有一颗未知星球

　　A planet, possibly four times the mass of Jupiter and with a lunar system, could be lurking in our solar system's outermost area, two US scientists theorize。

　　University of Louisiana researchers said if "Tyche" exists, the confirmed number of planets in our solar system would return to nine, with Pluto remaining a dwarf planet, DiscoveryNews.com reported Wednesday。

　　Astrophysicists John Matese and Daniel Whitmire analyzed comets passing through the inner solar system, discovering many of them had strange orbits。

　　The scientists said they believe the comets' orbits could be affected by the potential mystery planet, composed of hydrogen and helium, likely sucked into our solar system after being formed around another star。

　　Matese and Whitmire have been trying to track down Tyche's existence since 1999, but the majority of the astronomical community hasn't expressed confidence about Tyche's existence, DiscoveryNews.com said。

　　Ned Wright, principal investigator for NASA's Wide-Field Infrared Survey Explorer mission, told DiscoveryNews the theory behind Tyche is based on "ordinary evidence for an extraordinary claim."