Today's APOD is a view of some of the Volcanic Plains located on the Neptunian moon Triton; this view was produced by using topographic maps derived from images acquired by the NASA - Voyager 2 Spacecraft during its August 1989 Fly-By.
Triton, which is Neptune's largest moon, was the last solid object visited by the Voyager 2 Spacecraft on its epic 10-year tour of the Outer Solar System. This regional view shows a variety of Tritonian Terrains, including the smooth Volcanic Plains in the foreground, formed by Icy Lavas. Large areas of the Surface have been eroded, forming Mounds (very small Hills) and Depressions (small Valley-like Surface Features), with relief of tens to a few hundred meters (several hundred feet). The round Pits and Mounds visible across the center of the scene are probably the result of Volcanic (Pyroclastic) Explosions or Collapse Craters (such as areas where the Terrain collapsed under its own weight), the largest of which (at bottom center) is approx. 250 meters deep (820 feet) and approx. 15 Km (about 9 miles) across. Many of these Pits are aligned in Chains, similar to those seen in Basaltic Volcanic Areas on Earth (like the Craters visible in the so-called "Moon National Monument" located in the North American State of Idaho), or in many other places all over our Moon as well as on Mars. The difference is that the Lavas on Triton are made by Water and other Icy Materials (Mud, for instance) which erupted, through a phenomenon known as "Cryovolcanism", onto the Surface. In the distance, is visible one of two large walled smooth Plains whose origin is still unknown; these Plains are roughly 200 Km (about 124 miles) across.
In general, the Surface of Triton is very rugged (---> corrugated), scarred by rising blobs of ice (Diapirs), Faults, Volcanic Collapse Pits and Cryovolcanic Flows. The Surface appears also extremely young and shows a low amount of Inpact Craters. Triton's Surface may even be younger than the Surface of the Jovian moon Europa, one of the first objects visited by the Voyager Spacecrafts, and, as some Scientists speculated, something, on Triton, could still be geologically active. Although locally very rugged, Triton has no large Mountains or deep Basins and its regional relief is low, likely as a consequence of its high internal heat and the low strength of most of the Ices existing on its Surface.
This scene is on the order of approx. 500 Km (about 310 miles) across and is taken from a flyover movie across the Equatorial Regions of Triton; the vertical relief has been exaggerated by a factor of 25, to aid the vision and interpretation.
The frame has been colorized in Absolute Natural Colors (such as the colors that a normal - meaning "in average" - human eye would actually perceive if someone were onboard the NASA - Voyager 2 Spacecraft and then looked outside, towards the Neptunian moon Triton), by using an original technique created - and, in time, dramatically improved - by the Lunar Explorer Italia Team.
