The early Solar System was a turbulent and chaotic place with icy material hurled far from the Sun, becoming the Oort Cloud. Larger objects and planets were probably hurled into the Oort Cloud too, and some might have been kicked out of the Solar System entirely. If a similar situation happened in o...
Can you imagine the scientific buzz if we were to identify and send a lander to such a captured world? We're already pretty familiar with the type of matter in our own solar system, but something that formed in another star region could display very different characteristics. It would also be our first glimpse of what a truly alien world really looks like.
Given the dynamics of the galaxy and the early solar system, there is about a 7% chance that our solar system has a captured ice giant planet in the Oort cloud
So if there is a planet at the edge of the solar system, it is more likely to be an adopted child rather than one of the Sun’s offspring. It’s still most likely that the Oort Cloud has no large worlds, but this study shows that planetary systems don’t always form in isolation, and there are plenty of star systems that are likely blended families.