These two 591-second exposures of the rings of Neptune were taken by Voyager
2 on August 26, 1989 from a distance of 280,000 kilometers (174,000 miles).
The two main rings are clearly visible and appear complete over the region imaged.
Also visible in this image is the inner faint ring at about 42,000 kilometers
(25,000 miles) from the center of Neptune, and the faint band which extends
smoothly from the 53,000 kilometer (33,000 miles) ring to roughly halfway between
the two bright rings. The bright glare in the center is due to over-exposure
of the crescent of Neptune. Numerous bright stars are evident in the background.
Both rings are continuous. (Courtesy NASA/JPL)
within the Adams ring are the thre ring arcs, seen in the image to the left.
Evidence for incomplete arcs around Neptune first arose in the mid-1980's, when
stellar occultation experiments were found to occasionally show an extra "blink"
just before or after the planet occulted the star. Images by Voyager 2 in 1989
settled the issue, when the ring system was found to contain several faint rings,
the outermost of which, Adams, contains three prominent arcs now named Liberty,
Equality and Fraternity. The existence of arcs is very difficult to understand
because the laws of motion would predict that arcs spread out into a uniform
ring over very short timescales. The gravitational effects of Galatea, a moon
just inward from the ring, are now believed to confine the arcs. (Courtesy NASA/JPL)
This portion of one of Neptune's rings appears to be twisted. Scientists believe
it looks this way because the original material in the rings was in clumps that
formed streaks as the material orbited Neptune. The motion of the spacecraft
added to the twisted appearance by causing a slight smearing in the image. (Courtesy
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