So — the masthead image below, and the one at right — is an artist’s rendering (for the European Space Agency, or ESA) of data from its CHEOPS mission. The ring shown there. . . shouldn’t exist. In a few decades, it should have become a “shepherded” moonlet — coalesced to a small body inside the so-called “Roche Limit”. A much tighter orbit. But it likely has remained a tiny ringed world for over a thousand years — perhaps hundreds of thousands.

Perhaps it is an oddity of low temperatures; but perhaps it is evidence of a physics we as yet do not understand, in deeper space. If this was a ring around Saturn, due to its proportional distance — it would be very bright in the night sky — many times the diameter of Saturn itself. Do go read it all, and thereby update your now-outdated high school level understanding of low gravity orbital physics. And maybe help solve this. . . mystery:

…During a break from looking at planets around other stars, ESA’s CHaracterising ExOPlanet Satellite (Cheops) mission has observed a dwarf planet in our own Solar System and made a decisive contribution to the discovery of a dense ring of material around it.

The dwarf planet is known as Quaoar. The presence of a ring at a distance of almost seven and a half times the radius of Quaoar, opens up a mystery for astronomers to solve: why has this material not coalesced into a small moon?

Quaoar is one of a collection of small, distant worlds known as trans-Neptunian objects (TNOs). Roughly 3000 are known. As the name suggests, TNOs are found in the outer reaches of the Solar System, beyond the orbit of planet Neptune. The largest of the TNOs are Pluto and Eris. With an estimated radius of 555 km, Quaoar ranks around number seven on the size list, and is orbited by a small moon called Weywot, roughly 80 km in radius….

The Roche Limit

Any celestial object with an appreciable gravitational field will have a limit within which an approaching celestial object will be pulled to pieces. This is known as the Roche limit. Dense ring systems are expected to exist inside of the Roche limit, which is the case for Saturn, Chariklo and Haumea.

“So, what is so intriguing about this discovery around Quaoar is that the ring of material is much farther out than the Roche limit,” says Giovanni Bruno, INAF’s Astrophysical Observatory of Catania, Italy.

This is a mystery because according to conventional thinking, rings beyond the Roche limit will coalesce into a small moon within just a few decades. “As a result of our observations, the classical notion that dense rings survive only inside the Roche limit of a planetary body must be thoroughly revised,” says Giovanni….

[And the geekiest part of it, from the underlying science journal’s paper:]

Up to now, all known dense rings were located close enough to their parent bodies, being inside the Roche limit, where tidal forces prevent material with reasonable densities from aggregating into a satellite. Here we report observations of an inhomogeneous ring around the trans-Neptunian body (50000) Quaoar. This trans-Neptunian object has an estimated radius of 555 km and possesses a roughly 80-km satellite (Weywot) that orbits at 24 Quaoar radii. The detected ring orbits at 7.4 radii from the central body, which is well outside Quaoar’s classical Roche limit, thus indicating that this limit does not always determine where ring material can survive.

Our local collisional simulations show that elastic collisions, based on laboratory experiments, can maintain a ring far away from the body. Moreover, Quaoar’s ring orbits close to the 1/3 spin–orbit resonance with Quaoar, a property shared by Chariklo’s and Haumea’s rings, suggesting that this resonance plays a key role in ring confinement for small bodies….

Indeed. So somewhere, out there in the night sky, perhaps hundreds of millions of light-years from Earth, there may very well be a Saturn like body, in that system’s night sky which is itself not very bright — but its ring system… could fill up a third of the night sky, much brighter and well-defined than our Milky Way appears to be, on clear, cold mountain nights. It might make nights there… only marginally darker than… days.

And sentient beings may be pondering, right now, on that planet — why so many other Saturn like planets have such tightly bound, nearby ring systems. Indeed, indeed. Whoosh! Now you know.

नमस्ते