An artist's impression of Quaoar.
The solar system has plenty of rings around the planets, and even some of the asteroids have rings around them.
According to Nature magazine, "planetary rings" are discs containing many small chunks of ice and other materials that are in orbit around a larger object. Most rings are found within a critical distance of their host, known as the Roche limit, where the gravitational pull of the host prevents this material from accreting into objects.
Recently, astronomers discovered a brand-new ring system. They've been baffled by only this one because it is unlike everything else in the solar system.
As per a report by Science Alert magazine, Quaoar, a small dwarf planet that hangs out in the Kuiper Belt beyond Pluto, is also circled by a dense ring, circling at a distance so great that it should still be stuck together as a moon. The discovery means that scientists may need to revise our understanding of how moons and rings form and are affected by the gravitational interaction with their larger companion.
According to the European Space Agency, Quaoar is one of a collection of small, distant worlds known as trans-Neptunian objects (TNOs). Roughly 3000 are known. TNOs, as the name implies, are found in the Solar System's outer reaches, 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, which has a radius of roughly 80 km.
"Studying these dwarf planets is difficult because of their small sizes and extreme distances. Quaoar itself orbits the sun at almost 44 times the sun-Earth distance. Occultations are particularly valuable tools. Until recently, however, it has been difficult to predict exactly when and where they will take place."
"What is so intriguing about this discovery around Quaoar is that the ring of material is much farther out than the Roche limit," says astronomer Giovanni Bruno of the National Institute for Astrophysics in Italy.
"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."