Title:[0448] Eruption on Io Caption:A false-color image of the eruption of Io's volcano Loki constructed from four Voyager 1 pictures taken on 4 March 1979. The eruption is seen rising to an altitude of 200 km. Copyright: Credit:A NASA/JPL PHOTO

Title:[0295] Io from 376,951 kilometers Caption:This four-color mosaic of Io was taken by Voyager 1 on March 4, at 11:00 p.m. (PST) from a range of 376,951 kilometers and shows features about 8 kilometers in dimension. There are no obvious impact features identifiable in the hemisphere at this resolution, suggesting to scientists that Io's surface is quite young. The numerous features visible in this picture are being studied in higher resolution pictures taken during Voyager 1's encounter with Jupiter's minor Galilean moon. Many of these features are believed to be of internal, possibly volcanic origin. The surface is believed to consist of mixtures of salts and sulfur possibly brought to surface by volcanic activity. This surface is thought to be the source of material for the clouds of neutral and ionized atoms around Io's orbit observed by ground based telescopes and also the doubly ionized sulfur torus discovered by Voyager 1's Ultraviolet Spectrometer experiment. Copyright: Credit:NASA

Title:[0753] Volcanic caldera and lava flow on Io Caption:A Voyager 1 close-up of the surface of Io showing a volcanic caldera, which appears as a dark circular spot, and lava flows extending out from it. Copyright: Credit: National Optical Astronomy Observatories

Title:[0327] Io from 862,000 kilometers Caption:This full-disk image of Jupiter's satellite Io was made from several frames taken by Voyager 1 on 4 March 1979, as the spacecraft neared the satellite. Io is about 862,000 kilometers (500,000 miles) away. A variety of features can be seen in the photo linked to the intense volcanic activity on Io. Copyright: Credit:NASA

Title:[0752] Eruption on Io Caption:An eruption on the limb of Io seen in this Voyager image ejects sulfurous compounds to a height of about 100 miles. Copyright: Credit:National Optical Astronomy Observatories

Title:[4022] High Resolution Global View of Io Caption:The smallest features that can be discerned are 2.5 kilometers in size. There are rugged mountains several kilometers high, layered materials forming plateaus, and many irregular depressions called volcanic calderas. Several of the dark, flow-like features correspond to hot spots, and may be active lava flows. The picture is centered on the side of Io that always faces away from Jupiter; north is to the top. Color images acquired on September 7, 1996 have been merged with higher resolution images acquired on November 6, 1996 by the Solid State Imaging (CCD) system aboard NASA's Galileo spacecraft. Copyright: Credit:NASA/JPL

Title:[4023] Global View of Io in various colors Caption:These full disk views of Io, use images which were acquired by NASA's Galileo spacecraft when Io, the spacecraft, and the sun were nearly all aligned (near zero degrees phase angle). This angle best shows color variations on the surface. The left frame is an enhanced color view combining images obtained with the near- infrared, green, and violet filters of Galileo's Solid State Imaging (CCD) system. The white areas are rich in sulfur dioxide frost. Yellow, brown, and red areas are rich in other sulfurous materials. The upper right frame combines the green, near-infrared, and one micrometer filters. The lower right frame is a color ratio composite, in which ratios of different color combinations are displayed as red, green, and blue to reveal subtle color variations. North is to the top and the smallest features which can be discerned are 6 kilometers in size. These images were taken on December 18, 1996 at a range of 580,000 kilometers. Copyright: Credit:NASA/JPL

Title:[4027] Active Volcanic Plumes on Io Caption:This color image, acquired during Galileo's ninth orbit around Jupiter, shows two volcanic plumes on Io. One plume was captured on the bright limb or edge of the moon (see inset at upper right), erupting over a caldera (volcanic depression) named Pillan Patera.The plume seen by Galileo is 140 kilometers (86 miles) high. The second plume, seen near the terminator is called Prometheus. The shadow of the 75-kilometer (45- mile) high airborne plume can be seen extending to the right of the eruption vent. The resolution is about 6 kilometers (3.7 miles) per picture element. This composite uses images taken with the green, violet and near infrared filters of the solid state imaging (CCD) system on NASA's Galileo spacecraft. The images were obtained on June 28, 1997, at a range of more than 600,000 kilometers (372,000 miles). Copyright: Credit:NASA/JPL