BBC.A colossal new ring has been identified around Saturn.
The dusty hoop extends some 13 million km from the planet, about 50 times further out into space than its more familiar rings.
Scientists tell the journal Nature that the tenuous ring is probably made up of debris kicked off Saturn's moon Phoebe by small impacts.
They think this dust then migrates towards the planet where it is picked up by another Saturnian moon, Iapetus.
The discovery would appear to resolve a longstanding mystery in planetary science: why the walnut-shaped Iapetus has a two-tone complexion, with one side of the moon significantly darker than the other.