Scientists Solve The Mystery Of Saturn, Uranus and Neptune’s Rings

The mystery of the origin and diversity of the rings that surround Saturn, Uranus and Neptune has been reportedly solved by scientists. The experts have suggested that the planetary rings formed four billion years ago when large celestial objects travelled very close to the planets and got destroyed. Furthermore, there is a lot of diversity in the giant planets' rings as Saturn's rings comprise of 95 per cent icy particles, whereas the rings of Uranus and Neptune are darker and may include higher rock content.

The study was conducted by researchers from Japan's Tokyo Institute of Technology and Kobe University. The observation was based on the Late Heavy Bombardment period, which scientists believe occurred 4 billion years ago in the solar system. During this period the giant planets went through orbital migration. Thousands of Pluto-sized objects from the Kuiper belt are thought to have existed beyond Neptune. The researchers analyzed the possibility of these huge objects passing close to the giant planets, and in the process getting destroyed by their tidal force during the Late Heavy Bombardment period.

The team based their study on computer simulations to see if the tidal force of the giant planets disrupted the Kuiper belt objects when the latter came too close. The results showed that Saturn, Uranus and Neptune had numerous close encounters with the large Kuiper belt objects. Moreover, it was found that many of the fragments that constituted 0.1-10 per cent of the original mass of the passing objects were captured into the planet's orbits, and the combined mass of the captured pieces added up to explain the mass of the present rings around Saturn and Uranus.

Additionally, the researching team also simulated the captured fragments' long term evolution with the help of supercomputers at Japan's National Astronomical Observatory. The simulations showed that the captured fragments with an original size of several kilometers would go through repeated high-speed collisions and gradually shatter into small pieces. Furthermore, the collisions between the fragments circularized their orbits and led to the formation of the current rings present around the giant planets.

The study also showed why there is a compositional difference between the rings of the giant planets. As per the simulations, it was seen that the Kuiper belt objects faced strong tidal forces when they came near the giant planets. A report describes the difference in planetary ring composition as, "If Kuiper belt objects have layered structures such as a rocky core with an icy mantle and pass within close vicinity of Uranus or Neptune, in addition to the icy mantle, even the rocky core will be destroyed and captured, forming rings that include rocky composition. However if they pass by Saturn, only the icy mantle will be destroyed, forming icy rings."