An article published in the journal “Nature” describes a research that has revealed the size of the outer ring of the planet Saturn. It’s called Phoebe ring because it’s believed to have been created by dust particles coming from Phoebe, one of Saturn’s moons, as a result of impacts that projected them into space. This ring was discovered in 2009 and immediately its enormous size was noted. This new research using infrared images obtained from NASA’s WISE space telescope shows that it’s even larger than previously thought.

The Phoebe ring was discovered in 2009 thanks to NASA’s Spitzer space telescope but from the beginning its exact size was difficult to assess because of its nature. It’s composed mainly of extremely thin dust particles, medium size estimated between 10 and 20 microns. Only a small portion is composed of rocks so it’s really hard to see this ring.

Now a team led by Douglas Hamilton of the University of Maryland analyzed infrared photos taken by the WISE space telescope to evaluate the size of the Phoebe ring. The conclusion is that it extends to a distance ranging from 100 to 270 times Saturn’s size, that is between 6 and 16.2 million kilometers (3.75 million to 10.1 million miles).

It’s still an estimate because even looking at Phoebe ring at infrareds it’s difficult to see it all. In fact it could be even bigger but its borders may be too thin to be visible even with the best instruments.

This strange ring is probably originated from a strange moon. Phoebe has a retrograde orbit, which means that it orbits opposite to the planet’s rotation, and is inclined relative to the plane of the largest Saturn’s moons. Its composition is also different and this suggests that it’s a planetoid coming from the Kuiper belt captured by Saturn a few billion years ago.

The existence of the Phoebe ring may also explain the mystery of Iapetus, another Saturn’s moon. It’s an icy moon but one of its faces is very dark. It could be a contamination caused by materials coming from the Phoebe ring.

The Phoebe ring may have formed in the course of a few billion years and it’s for this reason that it has become so huge. The Saturnian system keeps on giving us surprises showing a history that is complex and very interesting in the study of the history of the solar system.

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