The Cassini spacecraft has found a previously unknown ring circling Saturn.
It appears to be composed of material blasted off the surface of two saturnian moons by meteoroid impacts.
The moons Janus and Epimetheus may be too small to hold on to dust kicked out by these impacts, so it escapes into space, spreading out into a ring.
The tenuous, wispy ring coincides with the orbits of these two moons, mission scientists noted.
Researchers expected meteoroid impacts on Janus and Epimetheus to kick particles off the moons' surfaces and inject them into an orbit around Saturn. But they were surprised to find such a well-defined ring at this location.