Scientists say that anywhere from ten to one hundred million years ago the planet Saturn had an unstable moon wobbling around it. It is estimated that it was 400 kilometers across. Some astronomers have named this now-extinct moon “Brevia.” for ‘brief.’ It was made of several different types of gases that had turned to ice. So it was, in effect, a giant snow ball.
Saturn is an immense planet. Several times the size of Earth, its gravitational field is monstrous. So the moon in question is in grave danger. Of disintegrating.
Like all planets, Saturn has a boundary, a limit, which, when crossed, inevitably draws all objects in it down into the planet’s atmosphere. This explains the flaming meteors we occasionally see in Earth’s night sky. These interstellar rocks crossed the limit and were drawn down into the atmosphere, where they are vaporized by friction.
But in Brevia’s case, something different happened when it got too close to Saturn’s limit. Instead of plummeting into the planet, the ice moon crumbled like a cookie. Hundreds of thousands of trillions of tons of ice are spread out from the ice moon’s demise. Now that the pieces are so small, they no longer feel the strongest effects of Saturn’s gravity, and continue to float above the planet in ever widening rings of debris. This phenomena probably occurred in a matter of weeks, encircling Saturn with its famous rings in about a month.
Modern observatories show that Saturn’s ring is on average just a few yards thick. Although in some places it bulges to nearly a quarter mile in thickness. And it’s really not just one ring, but a series of rings. This is because there are still some continent-size pieces of ice debris circling around the planet. These huge chunks act somewhat like a snow plow, clearing a path in the void.
The rings around Saturn are relatively stable. Scientists don’t expect the rings to dissipate for millions of years to come. So someday astronauts from our planet will have to navigate around them when they finally manage to land on Saturn. There is a theory gaining ground among some astronomers and astrophysicists that the static electricity generated by the ice debris circling Saturn could power a whole civilization on the giant planet. The planet is made up mostly of hydrogen and helium, which currently are in great demand here on Earth.
It’s possible we could see giant space barges from Saturn coming to our planet on a regular basis with these elements. It’s enough to make H.G. Wells dance a jig!
What about other planetary rings? Are there any around? And how about our own Moon? Will it someday give us a glorious circle of debris? Or will it come crashing down upon us, as in so many grade B sci-fi movies of the Fifties, to obliterate us?
Right now the Moon is 384 kilometers away from us. And in a widening orbit. But the principle of conservation of angular momentum insures that the Moon will never crash into us, break up into debris, or drift away completely. The principle in question states that once an object is rotating around another object, it would take a massive push of energy to dislodge it completely. In the case of our Moon, something like another Moon-sized object crashing into it. And there are no such objects lurking anywhere near us in the solar system. So if Elon Musk starts touting turning the Moon into a ring of debris to attract rich alien tourists, don’t invest in the stock!
In our own solar system Jupiter, Uranus, and distant Neptune all have rings as well. But they are not as well-defined as those of Saturn. Those rings are more like a mist, and even the most powerful telescopes can barely catch a glimpse of them. They were most likely not formed from crumbled moons, but from captured space dust that now swirls around Neptune, Uranus, and Jupiter. Sort of like gigantic dust bunnies on an endless merry-go-round under the solar system’s bed.
Looking farther afield, planet J1407B is around 430 light years away from our solar system. It sports an amazing series of rings around itself. They are over 200 times wider than the rings around the planet Saturn. To astronomers gazing in awe at it, the whole shebang looks like a giant dinner plate, with the planet J1407B itself little more than a pimple in the middle. The current theory is that this exo-planet’s rings are not due to disintegration, but rather are proof of re-integration. That is, the material of the rings is slowly coalescing into new moons. The proof for this, say scientists, is that there are already several small moons in between the rings. And more are likely to come together in the next several million years.
So whereas the disintegration of materials to make a planetary ring is often sudden and catastrophic, the opposite action of re-integration, or coalescence, is extremely slow.
What this means to you as a star gazer is that you may someday witness the formation of rings around a planet. But you’ll probably never live long enough to see the formation of a moon!