Credit: NASA/JPL-Caltech/R. Hurt (SSC)

This artist's conception shows a nearly invisible ring around Saturn -- the largest of the giant planet's many rings. It was discovered by NASA's Spitzer Space Telescope.

The ring is so diffuse that it reflects little sunlight, or visible light that we see with our eyes. But its dusty particles shine with infrared light, or heat radiation, that Spitzer can see.

The artist's conception simulates an infrared view of the giant ring. Saturn appears as just a small dot from outside the band of ice and dust. The bulk of the ring material starts about six million kilometers (3.7 million miles) away from the planet and extends outward roughly another 12 million kilometers (7.4 million miles). The ring's diameter is equivalent to roughly 300 Saturns lined up side to side.

The inset shows an enlarged image of Saturn, as seen by the W.M. Keck Observatory at Mauna Kea, Hawaii, in infrared light. The ring, stars and wispy clouds are an artist's representation.