Astronomy Picture of the Day
October 27, 2013

Titan's North Polar Wetlands (CTX Frame)
Titan's North Polar Wetlands (CTX Frame)

Credits: NASA/JPL/Space Science Institute - Credits for the additional process. and color.: Dr Paolo C. Fienga/LXTT/IPF

The vast Hydrocarbon Seas and Lakes located near the North Pole of the Saturnian moon Titan, sprawl out beneath the watchful eye of the NASA - Cassini Spacecraft. Scientists are studying images like these in the attempt of finding clues about how Titan's Hydrocarbon Seas and Lakes formed (and Titan, as you should know by now, is the only so far known Celestial Body in the Solar System - other than Earth, of course - that is known to have stable Bodies of Liquid on its Surface).


This view was made from Near-InfraRed images of Titan which were obtained by Cassini's Imaging Science Subsystem. Some kind of bright Material seems to surround the Lakes, and this circumstance could help us to explain why - currently - almost all the large Bodies of Liquid are found here, at Titan's North Polar Regions, rather than on other parts of this moon. The imaging data suggest that the Surface here is unique and the available explanations for this kind of environment range from the Collapse of Land - which probably occurred after a huge Volcanic Eruption - to the so-called "Karst Terrain" (---> such as an area of irregular Limestone in which the occurrence of Erosional Processes has produced Fissures, Sinkholes, underground Streams, and Caverns), where the liquids, in time, dissolved any soluble Bedrock. Karst Terrains on Earth can create some really spectacular Topography as it has occurred at the Carlsbad Caverns, in New Mexico


The largest of the dark shapes, at the upper right of the picture, is Kraken Mare, Titan's largest Sea and about the size of the Caspian Sea and Lake Superior put together. To its left, lies Ligeia Mare (about 300 miles - such as approx. 482,8 Km - across), which is the second largest Sea of Titan. Punga Mare (about 240 miles - or approx. 386,2 Km across) is below Ligeia Mare, and just above its leftmost finger there is the North Pole.


The Near-InfraRed images that made up this mosaic were obtained by Cassini's Imaging Science Subsystem on September 12, 2013. They were obtained in the Near InfraRed Band of Light (such as 938 nanometers), which is a Light Wavelength that is very close to the Visible Range of Light that human eyes can see. As a matter of fact, to an average human eyes, the Seas and Lakes here would still appear darker than the surrounding Terrain. To maximize signal from Titan's Surface through its Hazy Atmosphere, 10 image footprints (with 4 images per footprint) were combined to create this picture. The Terrain visible in this image is about 1000 miles (such as approx. 1609,3 Km) from top to bottom. Image scale is roughly 1760 feet (such as about 536,44 meters) per pixel.


Until now, Cassini's Imaging Science Subsystem had only been able to capture distant, oblique or partial views of this area; but three recent Fly-Bys carried out by the Spacecraft have provided us with much better Viewing Geometries, now that Sunlight has pierced the Winter darkness that shrouded Titan's North Pole since the time of Cassini's arrival in the Saturnian System, about nine years ago. A thick cap of Haze that once hung over the North Pole has also dissipated as the Northern Summer approached. And, thankfully, Titan's beautiful, almost cloudless and rain-free weather continued during all the Cassini's Fly-Bys which took place this past Summer of the AD 2013.


This picture (which is an Original NASA - Cassini Spacecraft b/w image-mosaic published on the NASA - Planetary Photojournal with the ID n. PIA 17473) has been additionally processed, contrast enhanced, magnified to aid visibility of the details, Gamma corrected and then colorized, according to an educated guess carried out by Dr Paolo C. Fienga/LXTT/IPF, in what they should be its Absolute Natural Colors (such as the colors that a human eye would actually perceive if someone were onboard the NASA - Cassini Spacecraft and then, once the thick layer of Atmospheric Haze that surrounds the whole globe of Titan has been overcome, looked outside, towards the North Polar Regions of the Saturnian moon Titan), by using an original technique created - and, in time, dramatically improved - by the Lunar Explorer Italia Team. Different colors, as well as different shades of the same color, mean, among others, the existence of different Elements present in the Atmosphere of Titan, each having a different Albedo (---> Reflectivity) and Chemical Composition.


Note: it is possible (but we, as IPF, have no way to be one-hundred-percent sure of such a circumstance), that the actual luminosity of Titan - as it is in this picture - would appear, to an average human eye, a little bit lower than it has been shown (or, better yet: interpreted) here.



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