Saturn's E ring in ultraviolet light

Visible from Earth only at times of ring plane crossing, Saturn's tenuous E Ring was discovered during the 1966 crossings and imaged again in 1980. From these observations, its colour is known to be distinctively blue. The E Ring was captured in ultraviolet light for the first time in this image taken with HST's Wide Field and Planetary Camera on 9 August 1995. Five individual images taken with a broadband 3000 A filter were combined, amounting to a total exposure time of 2200 sec. Shorter exposure images were also obtained with blue, red and infrared filters in order to characterize the ring's color.

The peak brightness of the E Ring occurs at 3.9 Saturn radii (235,000km), coinciding with the orbit of Enceladus. In the HST images it can be traced out to a maximum distance of approximately 8 Rs (480,000km). The vertical thickness of the ring, on the other hand, is smallest at Enceladus' orbit, with the ring puffing up noticeably at larger distances to 15,000 km or more thick.