Popular science: The "Lost Satellite" theory explains the two mysteries of Saturn

Xinhua News Agency, Beijing, September 21 (Reporter Zhang Ying) Saturn is the second largest planet in the solar system. One of the characteristics. For a long time, the scientific community has not concluded the cause of Saturn's rotation axis and the cause of the Saturn ring. A recent modeling study published by the American "Science" magazine believes that Saturn's self -rotation angle and the formation of the Saturn rings may be related to a satellite that was destroyed more than 100 million years ago.

"Cassini" detection data brings new progress

Like the gyroscope in the rotation, Saturn's self -rotating shaft will move periodic exercise with time. This phenomenon is called a spin. Because Saturn's rotation rate is almost the same as Neptune, astronomers have previously believed that Saturn's self -rotating angle is the result of the gravitational association with Neptune, also known as rail resonance.

The American Astronaut's "Cassini" detector surrounds the observation data of Saturn for more than 10 years, making the scientific community change. Scientists have discovered that Saturn's largest satellite Titani Liu is far away from Saturn at a faster speed than before. Based on the speed of Titan's migration and gravity, scientists speculate that Tusiu may be the cause of Saturn's self -tilt and maintained resonance with Neptune.

Whether this explanation can be established is that a key factor is Saturn's rotation inertia, and calculating rotation inertia needs to know the quality distribution of Saturn.

In the latest research, institutions such as Massachusetts Institute of Technology participated in the team using the "Cassini" detector's precise observation data on the gravitational field around Saturn to simulate the quality distribution of Saturn. As a result, the researchers surprised that Saturn's rotation inertia showed that it was close to the state of resonance with Neptune, but it was a little worse. This means that the two planets may be in a rail resonance state, but Saturn has now got rid of the resonance with Neptune.

Find the reason why Saturn gets rid of resonance

After the research team inspects the equation describing the law of Saturn's rotation, it is found that if one of the satellites that Saturn once owned by Saturn can explain the current state of Saturn. The research team believes that Saturn with 83 satellites today has at least one extra satellite, and they name this satellite "butterfly".

The research team simulates some basic attributes of "butterfly". It is equivalent to the eighth size of Saturn's third largest satellite, Tuwei, and has worked for hundreds of billions of years with "brothers and sisters". Its gravity to Saturn has kept Saturn from a certain rotation angle and forms track resonance with Neptune.

Researchers have speculated that at a certain stage from 200 million to 100 million years ago, "butterfly" entered a chaotic orbit area. After meeting with Tuwei Bayi and Tuschen several times, it was torn into fragments by a huge gravity when "crossing" with Saturn. Lost this satellite leaving Saturn from the resonance with Neptune and forming the current rotary axis inclination. Most of the "butterflies" may have hit Saturn, and a small part of the fragments may still be suspended on the orbit, and eventually decompose into small ice cubes, forming an iconic Saturn ring.

Researchers said that the "lost satellite" theory can not only explain the formation of Saturn's self -rotating axis, but also consistent with the research conclusions of the age of Saturn. Earlier studies have shown that the history of the Saturn Ring is relatively short compared to Saturn formed 4.5 billion years ago, and it has formed about 10 million to 100 million years ago.

Just like "broken cocoons into butterflies", "this satellite has been dormant for a long time, suddenly becomes active, and then (Saturn's) ring appears." Westum said. Westum emphasized that like any other theoretical hypothesis, the "lost satellite" theory must be tested by other researchers.

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