https://www.vice.com/en_us/article/v7dana/mysterious-instability-in-the-cosmos-puzzled-scientists-for-decades-now-we-have-an-answer > Our solar system is relatively tranquil at this point in time, with planets that follow predictable orbits around the Sun, but these cosmic surroundings weren’t always so calm. >  Scientists have long suspected that during the infancy of our solar system, tumultuous instabilities dramatically shifted the orbits of the gas giants—Jupiter, Saturn, Uranus, and Neptune—and may have even straight-up kicked a fifth mysterious planet out into the interstellar wilderness. However, the cause of this instability, which has also been observed in other star systems, has remained a matter of debate