On a Suspected Ring External to the Visible Rings of Saturn

Reexamination of a photograph of Saturn taken on 15 November 1966, when the earth was nearly in the ring plane, indicates that ring material may exist outside the visible rings, extending to more than 6 Saturnian radii. Although the suspected feature on the photograph appears to be real, the possibility of its being a developed pressure mark or a chance alignment of grains cannot be ruled out. The observed brightness in blue light was estimated to be m_B = 19.5 ± 0.5 per linear arcsecond, implying a normal optical thickness, τ ⋍ 10 ^-7, for ice-covered particles. For spacecraft passing through this region, the hazards are found to be minimal.