Scientists using data from NASA’s Cassini spacecraft and computer simulations said on Thursday that the destruction of a large moon that came too close to Saturn could explain both the birth of the gas giant planet’s magnificent rings and its unusual orbital tilt near Saturn. 27 degrees.
The researchers named this hypothetical moon Chrysalis and said it could have been torn apart by tidal forces due to Saturn’s gravitational pull, perhaps 160 million years ago – relatively recent compared to the planet’s formation date of more than 4.5 billion years ago.
According to the researchers, about 99% of the Chrysalis debris plunged into Saturn’s atmosphere, while the remaining 1% remained in orbit around the planet and eventually formed a large ring system that is one of the wonders of our solar system. They chose the name Chrysalis for the moon because it refers to the butterfly’s chrysalis stage before it transforms into its gorgeous adult form.
“Just as a butterfly emerges from a chrysalis, Saturn’s rings emerge from the primordial moon Chrysalis,” said Jack Wisdom, professor of planetary science at the Massachusetts Institute of Technology and lead author of the study, published in the journal Science.
The researchers calculated that Chrysalis was about the size of Iapetus, Saturn’s third largest moon, measuring just over 910 miles in diameter.
“We assume it was mostly water ice,” said planetary scientist and study co-author Burkhard Militzer of the University of California, Berkeley.
Saturn’s rings, predominantly composed of particles of water ice ranging in size from a grain of sand to the size of a mountain, extend up to 175,000 miles from the planet, but are typically only about 30 feet thick. While other large gaseous planets in the Solar System, including Jupiter, also have rings, they are minuscule compared to those of Saturn, the sixth planet from the Sun.
Located almost 10 times farther from the Sun than Earth, Saturn is the second largest planet in our solar system after Jupiter, with a volume 750 times that of Earth. Consisting mostly of hydrogen and helium, Saturn orbits 83 known moons, including Titan, the second largest moon in the solar system, larger than the planet Mercury.
Cassini circled Saturn 294 times from 2004 to 2017, collecting vital data, including gravity measurements that were key to the new study, before the robotic explorer made its deadly dive into the planet.
Saturn’s rings are visible from NASA’s Cassini spacecraft, which took the images that make up this mosaic, about 450,000 miles from Saturn on April 25, 2007. The destruction of a large moon that came too close to Saturn, scientists said Thursday, both explain the birth of the gas giant planet’s magnificent rings. (Photo: NASA/JPL-Caltech/Space Science Institute/Handout via Reuters)
A study published in 2019 found that the rings were added relatively recently, and a new study expands on those findings. In a new study, researchers have proposed a multi-step process to explain the formation of Saturn’s rings.
They said that the Saturn system formed with Chrysalis among the many moons present. At first, the planet’s axis of rotation was perpendicular to the plane of its orbit around the Sun, but the gravitational influence of the distant planet Neptune on the Saturnian system tilted Saturn’s axis of rotation.
The drama began when Titan’s orbit around Saturn began drifting outward – a process still in progress – destabilizing Chrysalis’s orbit, they say. Titan’s outward migration is thought to be relatively fast, around 4 inches per year, which doesn’t sound like much, but it gets a lot over time, especially for such a large moon.
The researchers said that Chrysalis’ orbit deteriorated, and the moon ventured so close to Saturn that it disintegrated.
“Saturn’s gravity tore it apart in the same way that Jupiter tore apart Comet Shoemaker-Levy 9,” Militzer said, referring to the comet that ended up hitting Jupiter in 1994.
“With the disappearance of the Chrysalis, Neptune could no longer change Saturn’s axis of rotation. Thus, the planet continued to rotate at an angle of 27 degrees,” added Militzer.
For comparison, the tilt of the Earth is about 23 degrees.