Astronomy Picture of the Day
April 4, 2014

Deep Blue (Part III)
Deep Blue (Part III)

Credits: NASA/JPL - Voyager 2 Project - Credits for the additional process. and color.: Dr Paolo C. Fienga/LXTT/IPF

These two beautiful images of the Gas-Giant Planet Neptune, were taken by the NASA - Voyager 2 Spacecraft's Narrow Angle Camera when the Probe was about 12 Million KiloMeters (such as approx. 7,452 Million Miles) from Neptune itself; the Resolution here (in both frames) is about 110 Km (such as approx. 68,31 miles) per pixel. During the 17,6 hours which passed between the left (Sx) and the right (Dx) image, the Great Dark Spot, located at about 22° South Latitude (slightly to the left of center), completed a little less than one full rotation of Neptune.

On the other hand, the smaller Dark Spot, found at approx. 54° South Latitude, completed a little more than one full rotation around Neptune, as it can be seen by comparing its relative position (as to the GDS) in the two pictures. The Great Dark Spot and the smaller one have a Relative Velocity of about 100 meters-per-second (such as approx. 360 Km-per-hour - or about 223,56 miles-per-hour); furthermore, the Light and Dark Bands that completely encircle Neptune, indicate the presence of a predominantly zonal (i.e.: East-to-West) motion of the Atmosphere. The diffuse (and long) White Atmospherical Feature located (slightly) to the North of the Great Dark Spot, is really near Neptune's Equator, and rotates with (about) the same period of the Great Dark Spot.

Streaks of Bright Clouds (possibly made - among other Chemical Components - of Water-ice Particles), located at the Southern Edge and just East of the Great Dark Spot, are its constant "companions", and keep changing the details of their appearance, often within just a few hours. The changing brightness of the Cloud Streaks could be, according to NASA, the result of (strong) Vertical Motion of Gases and other (perhaps solid) Particles located in the Upper Atmosphere of Neptune (but even this Theory - just as many others - is still far away from being considered as the correct and final one).

These frames (which are two Original NASA - Voyager 2 Spacecraft b/w frames published on the NASA - Planetary Photojournal with the ID n. PIA 01993) have been additionally processed, contrast enhanced, magnified to aid visibility of the details and then colorized in Absolute Natural Colors (such as the colors that a human eye would actually perceive if someone were onboard the NASA - Voyager 2 Spacecraft and then looked outside, towards the Gas-Giant Planet Neptune), 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 Neptune, 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 Neptune - as it is in these frames - would appear, to an average human eye, way lower than it has been shown (or, better yet: interpreted) here.

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