PIA01997.jpg = PIA01997: Rings of Neptune
These two 591-second exposures of the rings of Neptune were taken with the clear filter by the Voyager 2 wide-angle camera on Aug. 26, 1989 from a distance of 280,000 kilometers (175,000 miles). The two main rings are clearly visible and appear complete over the region imaged. The time between exposures was one hour and 27 minutes. [During this period the bright ring arcs in the outer bright ring were not visible in either picture (they were unfortunately on the opposite side of the planet for each exposure).] 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. Both of these newly discovered rings are broad and much fainter than the two narrow rings. These long exposure images were taken while the rings were back-lighted by the sun at a phase angle of 135 degrees. This viewing geometry enhances the visibility of dust and allows fainter, dusty parts of the ring to be seen. The bright glare in the center is due to over-exposure of the crescent of Neptune. The two gaps in the upper part of the outer ring in the image on the left are due to blemish removal in the computer processing. Numerous bright stars are evident in the background. Both bright rings have material throughout their entire orbit, and are therefore continuous. The Voyager Mission is conducted by JPL for NASA's Office of Space Science and Applications.
Voir l'image PIA01997: Rings of Neptune sur le site de la NASA.PIA01996: Neptune - Closest Approach
The Voyager spacecraft took this picture after closest approach to Neptune on Aug. 25 1989, using the clear filter of the wide-angle camera with an exposure time of 255 seconds. The view back towards Neptune at a phase angle of 135 degrees found the two known rings to be five to 10 times brighter than seen in backscattering during Voyager approach at much lower phase angle. This brightness increase implies a large percentage of microscopic particles within the rings. Although the dominant arc-like clump of the outer ring is not seen here, the inner ring appears brighter than the outer ring at the longitudes seen in this image. A faint sheet of material is also revealed that extends from the faint ring at a radius of 53,200 kilometers(33,000 miles). A new and even fainter ring was discovered in this image at about 41,000 kilometers (25,400 miles), seen running from the lower left corner to about one-third the way across the top of the frame. This ring is quite broad, about 2,500 kilometers (1,550 miles) in radial width. In contrast to the two previously discovered rings, this feature is quite diffuse and has no well defined radial boundaries. The Voyager imaging experiment has now detected ring material in all of the radial regions in which it has been detected by groundbased stellar occultation experiments. The Voyager spacecraft was 720,000 kilometers (446,400 miles) from Neptune at the time of this exposure. The Voyager Mission is conducted by JPL for NASA's Office of Space Science and Applications.
Voir l'image PIA01996: Neptune - Closest Approach sur le site de la NASA.PIA02207: Neptune's Rings
This wide-angle Voyager 2 image, taken through the camera's clear filter, is the first to show Neptune's rings in detail. The two main rings, about 53,000 km (33,000 miles) and 63,000 km (39,000 miles) from Neptune, are 5 to 10 times brighter than in earlier images. The difference is due to lighting and viewing geometry. In approach images, the rings were seen in light scattered backward toward the spacecraft at a 15-degree phase angle. However, this image was taken at a 135-degree phase angle as Voyager left the planet. That geometry is ideal for detecting microscopic particles that forward-scatter light preferentially. The fact that Neptune's rings are so much brighter at that angle means the particle-size distribution is quite different from most of Uranus' and Saturn's rings, which contain fewer dust-size grains. However, a few components of the Saturnian and Uranian ring systems exhibit forward-scattering behavior: The F ring and the Encke Gap ringlet at Saturn, and 1986U1R at Uranus. They are also narrow, clumpy ringlets with kinks, and are associated with nearby moonlets too small to detect directly. In this image, the main clumpy arc, composed of three features each about 6 to 8 degrees long, is clearly seen. This image was obtained when Voyager was 1.1 million km (683,000 miles) from Neptune. Exposure time was 111seconds. The Voyager Mission is conducted by JPL for NASA's Office of Space Science and Applications.
Voir l'image PIA02207: Neptune's Rings sur le site de la NASA.
PIA02256: Neptune: Ring Arcs
The Voyager spacecraft was 8.6 million kilometers (5.3 million miles) from Neptune when it took this 61 second exposure through the clear filter with the narrow angle camera on August 19, 1989. The Voyager cameras were programmed to make a systematic search for faint ring arcs and new satellites. The bright upper corner of the image is due to a residual image from a previous long exposure of the planet. The portion of the arc visible here is approximately 35 degrees in longitudinal extent, making it approximately 38,000 kilometers (24,000 miles) in length, and is broken up into three segments separated from each other by approximately 5 degrees. The trailing edge is at the upper right and has an abrupt end while the leading edge seems to fade into the background more gradually. This arc orbits very close to one of the newly discovered Neptune satellites, 1989N4. Close-up studies of this ring arc will be carried out in the coming days which will give higher spatial resolution at different lighting angles. The Voyager Mission is conducted by JPL for NASA's Office of Space Science and Applications.
Voir l'image PIA02256: Neptune: Ring Arcs sur le site de la NASA.
PIA02224: Neptune's Rings
This 591-second exposure of the rings of Neptune were taken with the clear filter by the Voyager 2 wide-angle camera. The two main rings are clearly visible and appear complete over the region imaged. Also visible in this image is the inner faint ring and the faint band which extends smoothly from the ring roughly halfway between the two bright rings. Both of these newly discovered rings are broad and much fainter than the two narrow rings. The bright glare is due to over-exposure of the crescent on Neptune. Numerous bright stars are evident in the background. Both bright rings have material throughout their entire orbit, and are therefore continuous. The Voyager Mission is conducted by JPL for NASA's Office of Space Science and Applications.
Voir l'image PIA02224: Neptune's Rings sur le site de la NASA.
PIA00053: Neptune Rings and 1989N2
In this Voyager wide-angle image taken on Aug. 23 1989, the two main rings of Neptune can be clearly seen. In the lower part of the frame the originally announced ring arc, consisting of three distinct features, is visible. This feature covers about 35 degrees of longitude and has yet to be radially resolved in Voyager images. From higher resolution images it is known that this region contains much more material than the diffuse belts seen elsewhere in its orbit, which seem to encircle the planet. This is consistent with the fact that ground-based observations of stellar occultations by the rings show them to be very broken and clumpy. The more sensitive wide-angle camera is revealing more widely distributed but fainter material. Each of these rings of material lies just outside of the orbit of a newly discovered moon. One of these moons, 1989N2, may be seen in the upper right corner. The moon is streaked by its orbital motion, whereas the stars in the frame are less smeared. The dark area around the bright moon and star are artifacts of the processing required to bring out the faint rings. This wide-angle image was taken from a range of 2 million kilometers (1.2 million miles), through the clear filter. The Voyager Mission is conducted by JPL for NASA's Office of Space Science and Applications.
Voir l'image PIA00053: Neptune Rings and 1989N2 sur le site de la NASA.PIA01493: Neptune's Rings
| | PIA01493: Neptune's Rings
PIA02202.jpg = PIA02202: Neptune - Full Ring System
This pair of Voyager 2 images (FDS 11446.21 and 11448.10), two 591-s exposures obtained through the clear filter of the wide angle camera, show the full ring system with the highest sensitivity. Visible in this figure are the bright, narrow N53 and N63 rings, the diffuse N42 ring, and (faintly) the plateau outside of the N53 ring (with its slight brightening near 57,500 km).
Voir l'image PIA02202: Neptune - Full Ring System sur le site de la NASA.