page_title: Ithaca Chasma
hierarchical_section_title: Ithaca Chasma
caption_attribution_description: English: With this full-disk mosaic, Cassini presents the best view yet of the south pole of Saturn's moon Tethys. The giant rift Ithaca Chasma cuts across the disk. Much of the topography seen here, including that of Ithaca Chasma, has a soft, muted appearance. It is clearly very old and has been heavily bombarded by impacts over time. Many of the fresh-appearing craters (ones with crisp relief) exhibit unusually bright crater floors. The origin of the apparent brightness (or "albedo") contrast is not known. It is possible that impacts punched through to a brighter layer underneath, or perhaps it is brighter because of different grain sizes or textures of the crater floor material in comparison to material along the crater walls and surrounding surface. The moon's high southern latitudes, seen here at the bottom, were not imaged by NASA's Voyager spacecraft during their flybys of Tethys 25 years ago. The mosaic is composed of nine images taken during Cassini's close flyby of Tethys (1,071 kilometers, or 665 miles across) on Sept. 24, 2005, during which the spacecraft passed approximately 1,500 kilometers (930 miles) above the moon's surface. This view is centered on terrain at approximately 1.2 degrees south latitude and 342 degrees west longitude on Tethys. It has been rotated so that north is up. The clear filter images in this mosaic were taken with the Cassini spacecraft narrow-angle camera at distances ranging from 71,600 kilometers (44,500 miles) to 62,400 kilometers (38,800 miles) from Tethys and at a Sun-Tethys-spacecraft, or phase, angle of 21 degrees. The image scale is 370 meters (1,200 feet) per pixel.
context_page_description: Ithaca Chasma is a valley of Saturn's moon Tethys, named after the island of Ithaca, in Greece. It is up to 100 km wide, 3 to 5 km deep and 2,000 km long, running approximately three-quarters of the way around Tethys' circumference, making it one of the longer valleys in the Solar System. Ithaca Chasma is approximately concentric with Odysseus crater.
  Ithaca Chasma may have originated when the global salt water ocean inside Tethys froze. This would have caused the surface to crack in order to accommodate the resulting increase in volume. Another hypothesis is that Ithaca Chasma is the outermost ring of the Odysseus impact basin. The chasma is from 4 to 0.4 billion years old, and slightly older than Odysseus.
context_section_description: Ithaca Chasma /ˈɪθəkə ˈkæzmə/ is a valley (graben) of Saturn's moon Tethys, named after the island of Ithaca, in Greece. It is up to 100 km wide, 3 to 5 km deep and 2,000 km long, running approximately three-quarters of the way around Tethys' circumference, making it one of the longer valleys in the Solar System.  Ithaca Chasma is approximately concentric with Odysseus crater.
  Ithaca Chasma may have originated when the global salt water ocean inside Tethys froze. This would have caused the surface to crack in order to accommodate the resulting increase in volume. Another hypothesis is that Ithaca Chasma is the outermost ring of the Odysseus impact basin. The chasma is from 4 to 0.4 billion years old, and slightly older than Odysseus.
caption: Tethys and Ithaca Chasma
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