Astronomy Picture of the Day
May 7, 2014

Double Crescent on Titan
Double Crescent on Titan

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

Titan's South Polar Vortex mimics the moon itself, creating - as you can (barely) see in this frame, taken by the NASA - Cassini Spacecraft on December, 1, 2013 - a somehow elegant "crescent within a crescent". In fact, situated above the (surrounding) South Polar Atmosphere, the raised Walls of the Vortex, which stand along its Sunward Side, can just catch the grazing Sunlight, thus creating a "crescent" of its own. Titan (that, as you should know by now, is approx. 3200 miles - such as about 5149,88 Km - across) is Saturn's largest moon and possesses an extremely dense and ultra-dynamic Atmosphere, whose true characteristics are still a mistery.

Speaking of unanswered questions as well as problems which are still unsolved, we have to say - as IPF - that the true nature (---> meaning Seasonal or Permanent) of the South Polar Vortex keeps being, up to now, an highly controversial subject in the Planetary Scientists' Community. However, a definitive answer about the aforementioned question - and we like to say "obviously" -, will come, in a way or another, in time. For now, the only - truly - wise thing to do, is to keep looking...

This view looks toward the Trailing Hemisphere of Titan and North is up. The image was taken with the NASA - Cassini Spacecraft Wide-Angle Camera - as we wrote herebefore - on December, 1, 2013, by using a Spectral Filter which preferentially admits Wavelengths of Near-InfraRed Light centered at 939 nanometers. This frame was obtained at a distance of approximately 108.000 miles (such as about 173.808,72 Km) from Titan and the scale is roughly 6 miles (such as approx. 9,65 Km ) per pixel.

This frame (which is an Original NASA - CASSINI Spacecraft's b/w and NON Map-Projected image published on the NASA - Planetary Photojournal with the ID n. PIA 17163) has been additionally processed, contrast enhanced, magnified to aid the visibility of the details, Gamma corrected and then colorized - according to an educated guess (or, if you wish, an informed speculation) carried out by Dr Paolo C. Fienga - 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 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 other things, the existence of different Elements (Gases) 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 frame - 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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