A Mysterious Ring Surrounding Mini-Planet 'Quaoar' Puzzles Astronomers

A mini-planet orbiting in the frigid outer reaches of the solar system has a Saturn-like ring of dust and debris that defies the rules of physics, a new study has revealed. Space.com reports: The planet in question is called Quaoar and it's the seventh largest of the known dwarf planets of which Pluto is the king. Discovered in 2002 and about 697 miles wide (1,121 kilometers), Quaoar is one of the so-called trans-Neptunian objects, small planets orbiting beyond the solar system's outermost planet Neptune. Residing in the Kuiper Belt, the doughnut-shaped ring of rocky and icy debris in the outer solar system, Quaoar is a proud owner of its own moon, the 100-mile-wide (160 km) Weywot. And a recent observation campaign revealed that it also has a ring of material in its orbit. [...] Quaoar's ring is at a very unusual distance from its parent body. In fact, before astronomers discovered Quaoar's ring in observations from several telescopes conducted between 2018 and 2021, they had thought that it was impossible for a ring to exist at such a distance. With a radius of about 2,420 miles (3,885 km) from Quaoar's center, the ring is too far away from the dwarf planet that its gravity should no longer be able to keep the material dispersed. Instead, it should coalesce under its own gravity and form another moon, just like Weywot. By not having done that, the ring has breached what astronomers call the Roche limit, the first known ring around a celestial body to have done so. [...] Now astronomers have to either rethink the Roche limit or come up with another explanation for the existence of Quaoar's ring. The study was published in the journal Nature.

Read more of this story at Slashdot.