Astronomy Picture of the Day
January 15, 2013

The Amirani Flow Field
The Amirani Flow Field

Credits: NASA/JPL/Univ. of Arizona - Galileo Project - Credits for the additional process. and color.: Dr Paolo C. Fienga/Lunar Explorer Italia/IPF

Today's APOD - which takes back again to the Jovian Volcanic moon, Io - is an image-mosaic that combines 3 (three) frames collected by the NASA - Galileo Orbiter in February of the AD 2000 and during the Summer of the AD 1999; all these frames have been taken to highlight new details of the longest active Lava Flow that is known in the whole Solar System. The area, called Amirani, has been known to be the home of a number of Volcanic Hot Spots ever since the NASA's two Voyager Spacecraft flew by Jupiter in the AD 1979. Images collected by the Galileo Orbiter in 1999 showed that these hot areas were part of a single and immense Lava Flow Field, and the newest images confirm that the Amirani Flow Field is indeed a quilt work of Dark Lava Flows (remember that, on Io, the most recent Lavas are dark because they are way too hot to be covered by Sulphur-Dioxide Plumes).

Fresh Lava is leaking out of at least 5 (five) areas located at the Northern End of the Amirani Flow Field and from at least 3 (three) places in the middle. However, it is likely that the Lava first comes to the Surface near the Southern End of the Flow Field; then, since it is very liquid, it travels under a frozen Layer of older Lava, breaking out onto the Surface only after traveling hundreds of kilometers from the Vent (---> the Opening to the Surface). Just out of curiosity, the "small" breakouts located in the Amirani Flow Field produced (and, perhaps, are still producing, even now!) Lava Flows which are considerably larger than the ones that were seen on Earth, at the Kilauea Volcano in Hawaii, in the month of October of the AD 2000. These observations, however, even though they refer to a very distant Celestial Body, may also help Planetary Scientists to explain how very large, ancient Lava Flows might have formed on our Home Planet Earth.

While the behavior of the Lava - once it is on the Surface of Io - it is relatively easy to explain, the way said Lava comes to the Surface is more complicated. Small, white, diffuse Halos surrounding the darkest Lava Flows are probably Sulphur-Dioxide-rich Snows and Frosts that have been vaporized by the hot Magma. The bright red Material visible to the South of the Amirani Flow Field is likely to contain a large fraction of Sulphur Droplets, while some Sulphur-rich Material appears to be bubbling out all along the East-West Crack located at the Southern End of Amirani and this may be the Crack along which the Lava rises up to the Surface. Finally, the main Amirani Plume appears to emanate from a fuzzy, purplish area located within the Southern part of the Flow Field (and this Southern area may be, as we wrote before, a plausible alternative location from which the Fresh, Molten Lava could actually come up to the Surface).

The image-mosaic shows an area approx. 500 Km (such as about 310,5 miles) long and approx. 180 Km (such as about 112 miles wide). Black and white images at 210 meters (690 feet) per picture element were combined with color data at about 1,3 Km (such as approx. 0,8 miles) per picture element.

This picture (which is an Original NASA - Galileo Orbiter false-color image mosaic published on the NASA - Planetary Photojournal with the ID n. PIA 02566) has been additionally processed and then re-colorized in Absolute Natural Colors (such as the colors that a human eye would actually perceive if someone were onboard the NASA - Galileo Orbiter and then looked down, towards the Amirani Flow Field located of the Jovian moon Io), 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 on the Surface of Io, each having a different Albedo (---> Reflectivity) and Chemical Composition.

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