- The seven icy rings of Saturn each rotate at their own speed, behaving like a “mini solar system”.
- Planetary scientist James O’Donoghue made a wonderfully simple animation to show how it works.
- But the rings are temporary – Saturn is slowly swallowing them, according to O’Donoghue’s research.
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If star-jumping aliens ever visited our solar system, Saturn is probably the planet they would remember.
The seven giant rings that surround its equator make Saturn the most distinct planet orbiting the sun. It may not be obvious in the images of the planet hula-hoop, but the chunks of ice and rock that make up those rings circle Saturn at speeds nearly 70 times the speed of sound. Plus, each ring moves at its own pace.
“In a way, the ring system is like a mini solar system”, James O’Donoghuea planetary scientist with Japan’s JAXA space agency told Insider. “Objects close to Saturn orbit faster otherwise they would fall, while objects farther away can afford to go slower. This is the same for planets.”
In his spare time, O’Donoghue performs animations on physics and the solar system. Some of his others have shown that there is no “dark side” to the moon, that the true center of the solar system is not the sun, and that the Earth has two types of days.
When he put his skills to represent the rings of Saturn to work, O’Donoghue created an animation (below) that shows how each ring moves through its own movements in a beautiful circular dance.
In the animation, the line labeled “synchronous orbit” is in sync with Saturn’s spin, so it shows what parts of the rings you would see over time if you were at that point on the planet.
Saturn’s slowest outer ring rotates at about 37,000 mph (16.4 kilometers per second), slower than Saturn’s own rotation. The innermost chunks of ice and rock traverse space at approximately 52,000 mph (23.2 kilometers per second).
Up close, Saturn’s rings are not as chaotic as their speeds might make them appear. According to O’Donoghue, the ice grains on neighboring slopes only move at a few inches per minute relative to each other.
“That speed is like walking one step every 30 minutes, or similar to rush hour traffic,” saying On twitter. “So the collisions are not very dramatic.”
Saturn is slowly swallowing its rings
In addition to moving incredibly fast, Saturn’s rings are very long and thin. If you unfolded them, as O’Donoghue did in the image below, all the planets would fit comfortably within their length.
But in total, the rings are only 1 / 5,000 the mass of our moon.
“In other words, our moon could be used to make 5,000 Saturn ring systems,” O’Donoghue told Insider. “This highlights how extremely thin and fragile Saturn’s rings are.”
This fragility is a subject of scientific investigation of O’Donoghue. By studying Saturn’s upper atmosphere, he and his colleagues discovered that the rings are slowly disappearing. Thousands of kilograms of annular material rain down on the planet every second. At that rate, the rings shouldn’t last more than 300 million years in their current “full” form, he said.
“Saturn’s ring system is not exactly stable, it looks more like a temporary debris field from some ancient moon or comet that got too close and broke apart, rather than a permanent feature,” O’Donoghue added. “We can consider ourselves lucky to live in a time when the rings of Saturn have such an enormous presence in the solar system.”