Saturn's rings burst out of shadow and curve gracefully around the planet. Prometheus (86 kilometers, or 53 miles across at its widest point) appears as a bright speck touching the inside of the narrow F ring. Atlas (30 kilometers, 19 miles across at its widest point) is also visible, faintly, upward and to the left of Prometheus, just outside the A ring edge. Saturn's shadow cuts across the rings at top right. Several dark, narrow spokes are faintly visible near the B-ring ansa, left of center.
Image: Cassini-Huygens spacecraft
Source: NASA/JPL/Space Science Institute
Question: Has Saturn got a new ring?
Answer: Saturn does not actually have a new ring – this one has been there for a long time, but it is newly discovered.
For many years, astronomers have thought that there might be a thin ring in this region of space. This is because of the strange colouring seen on one side of Iapetus, a small moon of Saturn. Unusually, the two sides of this moon are very different colours. Moreover, the colour of the darker side closely matches the colour of another moon, Phoebe. Astronomers thought that dust from Phoebe might be being blown into space and landing on Iapetus. However, until now, no one had ever been able to find this dust.
Using the Spitzer Space telescope, scientists from the Univeristy of Virginia and the University of Maryland solved the problem by studying the area in infrared light. The thin ring is too sparse to reflect visible light, but it does glow weakly in infrared light.
A spokesman from NASA’s Jet Propulsion Laboratory described the ring as 'a thin array of ice and dust particles lies at the far reaches of the Saturnian system and its orbit is tilted 27 degrees from the planet's main ring plane.'
As Iapetus makes its journey around Saturn, its leading edge passes through this ring, picking up dust particles and making it darker than the trailing edge. "While there are many details yet to be worked out, we think we now understand the essence of why Iapetus looks the way it does," said Carolyn Porco, the leader of the imaging team at the Space Science Institute in Boulder, Colorado.
Learn more about Saturn, its magnificent rings, moons, surface and atmosphere on the Museum Victoria and NASA websites.