A missing planet may explain the solar system's chaotic past

Researchers examined a turbulent period in the solar system's early history, roughly 4 to 4.5 billion years ago, when the giant planets experienced dramatic orbital changes. During this phase, known as the Nice Model instability, planets such as Jupiter, Saturn, Uranus and Neptune are believed to have shifted from their original positions, passing close to one another and creating powerful gravitational disturbances.

Scientists have long questioned how the regular moons of these planets survived such a chaotic era. To investigate, researchers analyzed 122 computer simulations selected from thousands of possible scenarios because they closely matched the present structure of the outer solar system.

The simulations explored models that began with 5 or 6 giant planets rather than the 4 known today. Some versions of the Nice Model suggest that 1 or even 2 additional giant planets once existed before being ejected from the solar system.

The results indicate that the moon systems of Jupiter and Uranus faced a high risk of destruction during this period. According to the study, the probability that both planetary systems would retain their original moons was less than 15%. Among all the simulations tested, only one scenario allowed both the planets and their original moons to survive intact.

The findings suggest that close encounters with other giant planets would have been especially damaging for Uranus. Instead of being flung into space, many of its moons may have collided with one another, creating large amounts of icy debris. Over time, that material could have merged to form new moons.

Researchers believe this process may explain the origin of Miranda, one of Uranus's most unusual moons. The study also suggests that Uranus's moons may have experienced major collisions on more than one occasion, including during the event that tilted the planet onto its side and later during the period of planetary instability.

While the simulations offer new clues about the solar system's violent past, the researchers caution that computer models cannot capture every detail of events that occurred billions of years ago. Further studies will be needed to determine exactly how individual moons formed and evolved.

Earlier, Qazinform News Agency reported that Jupiter’s dust ring may have helped form early planets.