5.10.2023

Planet Saturn with shadow of moon Dione in lower right, taken by Voyager 1 spacecraft, 1980.

Saturn’s rings, the origins of which have long puzzled astronomers, might be debris from two colliding moons.

NASA and its partners published research in the Astrophysical Journal, suggesting that colliding icy moons shattered and the planet’s gravity pulled the debris into orbit.

The theory for the formation of the rings was tested 200 times by the high-resolution smooth particle hydrodynamics (SPH) simulation, and was based on the collision of two mid-size icy satellites.

“We conclude that the impact of two destabilized icy moons is a promising scenario for the recent formation or rejuvenation of Saturn’s rings,” says lead author Dr. Luis Teodoro.

The authors speculate that the collision occurred due to instability in the previous satellite system a few hundred million years ago.

“We find that this kind of impact can produce a wide distribution of massive objects and scatter material throughout the system.”

The simulation model followed the trajectory of the two moons colliding at different angles and varying velocities. When the objects crashed, the scientists watched the directions of the particles’ paths.

“We find that a range of plausible impacts can deliver significant mass directly inside the Roche limit, with a ring-like composition of pure ice,” they write.

For a planet to possess rings, the debris – whether ice or rock – needs to circulate around what is called the Roche limit or Roche radius. The Roche limit indicates the gravitational boundary of a planet before an orbiting celestial object is torn apart or misshapen.

They believe the ice is being pulled into Saturn’s atmosphere as it passes the Roche limit.  

Saturn’s rings appear to be young and dwindling. Saturn’s ring systemextends up to 282,000 kilometers from the planet, yet the vertical height is typically about 10 meters in the main rings.

Saturn is a gas giant, with 146 moons, (and still counting,) some larger than Mercury or Pluto, other are as small as a sports arena.

“Future work on the long-term evolution of the orbit-crossing debris, combined with further and more detailed modeling of collisions between both icy moons and smaller fragments, will help to constrain the implications of this scenario for Saturn’s rings, its moons, their craters, and other surface environments.”

Quelle: COSMOS