New research suggest that one fifth giant planet, the other four are Uranus, Saturn, Jupiter and Neptune, was disqualified from our system about 4,000 million years. That mysterious world today could be thousands of light years away and, which is just as surprising, it is possible to have moons that, if they meet the appropriate conditions are still warm enough to support life. A summary of the study can be found at arXiv.org.
Our solar system is an extraordinarily organized. The planets move in orbits broad, almost circular. It is an exemplary system, very different from other discovered where the orbits of the planets around their stars are very steep or elliptical. Some of these worlds are so close to their suns at risk of dying exhausted.
David Nesvorny, the Southwest Research Institute in Boulder, Colorado, has conducted a series of simulations showing that this was not always so. He believes that in the past the Solar System hosted fifth giant planet with several dozen times the mass of Earth. This world may have large located between Saturn and Uranus or Neptune beyond. Apparently, a close encounter with Jupiter system became unstable and the fifth giant was expelled from his place of birth. The simulation Nesvorny, the Discovery Channel explains on its website, indicates that our Solar System was originally very chaotic. Smaller bodies also "got a kick" and were sent away, and there was a "bombardment" of material that the Moon is printed on its surface in the form of scars.
What happened is not as incredible as it seems. Many planets may have been unaccompanied ejected from their planetary systems and float freely in space. Recently, a team of researchers from Japan and New Zealand found ten bodies dark mass of Jupiter, far from any star. These lonely planets are quite common in our galaxy.
In addition, the expelled planet could have their own moons. In that case, these partners could stay warm in the absence of its star and perhaps keep enough heat to support life.