Astronomy Picture of the Day
March 2, 2013

Ontario Lacus and the South Polar Region of Titan
Ontario Lacus and the South Polar Region of Titan

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

This view of Titan’s South Pole reveals the intriguing Dark Feature named Ontario Lacus and a host of smaller features dotting the whole South Polar Region. The true nature of this Surface Feature, seen here at left of center, is not yet known with absolute certainty. However, the Feature’s extremely dark coloration, the shore-like smoothness of its perimeter, and its presence in an area where frequent Convective Storm Clouds have been observed by the NASA - Cassini Spacecraft and Earth-based telescopes, made it the best candidate for an open body of liquid on Titan when this image was taken, in June 2005. This interpretation has, afterwards, been strengthened by the sighting of Surface Features having similar morphologies, but this time in Titan’s North Polar Regions during the Fly-By of this Saturnian moon that occurred in late February of the AD 2007. The possibility that those Northern Features, the sizes of small Seas, are either completely or partially filled with Liquid Hydrocarbons has been significantly strengthened also by the Radar Data collected by Cassini and which overlap portions of the Northern Features seen by the Cassini's Imaging Science Subsystem.

Previously, scientists had speculated that Ontario Lacus might simply be a Broad Depression filled by dark, Solid Hydrocarbons falling from the Atmosphere onto Titan’s Surface. In this case, the smoothed outline might be the result of a process unrelated to Rainfall, such as a so-called "Sinkhole" (---> a cavity in the ground, especially in a limestone formation, caused by water erosion and providing a route for Surface Water to disappear) or a "Volcanic Caldera". However, the strong likelihood that the Dark and Smooth North Polar Features are actually Lakes and Seas has made imaging scientists more confident that Ontario Lacus, and the smaller Dark Features dotting the South Polar Regions of Titan, also hold liquid. If correct, this new revelation would mean that each Pole on Titan is, in fact, a large Wetlands Area. The brightest (and almost white) Features seen here (from about 3 to 6 o'clock of the picture), are Methane Clouds (perhaps mixed with Water-Ice Clouds).

The original frame that we show you today, was taken by the NASA - Cassini Spacecraft during the distant Fly-By of Titan that took place in June 6, of the AD 2005, by using a combination of Spectral Filters sensitive to Wavelengths of Polarized InfraRed Light, allowing Cassini to see through the obscuring smog of Titan's Atmosphere and all the way down to the Surface. The image was acquired from an approximate distance of 450.000 Km (such as about 279.450 miles) from Titan. Resolution in the original image is approximately 3 Km (such as 1,863 miles) per pixel.

This picture (which is an Original NASA - Cassini Spacecraft b/w frame published on the NASA - Planetary Photojournal and identified by the n. PIA 06241) has been additionally processed and then colorized, according to an educated guess carried out by Dr Paolo C. Fienga (LXTT-IPF), in Absolute Natural Colors (such as the colors that a human eye would actually perceive if someone were onboard the NASA - Cassini Spacecraft and then looked outside, towards the South Polar Region 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 and on the Surface 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 the Albedo Features seen in this frame would appear, to an average human eye, way lower than it has been shown (better yet: interpreted) here.

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