Astronomy Picture of the Day
March 25, 2013

Tvashtar Catena
Tvashtar Catena

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

The pictures forming this mosaic of the Tvashtar Catena (such as a Chain of Volcanic Craters), located on Jupiter's "Volcanic moon", Io, were taken by the NASA - Galileo Spacecraft on October 16, 2001, and they completed a series of views depicting the changes which occurred in this Region over a period of nearly two years. Streaks of Light and Dark Deposits that radiate from the Central Volcanic Crater, or "Patera," are the remnants of a tall Plume that was seen erupting in earlier images. This image as well as many others from November 1999, February 2000, December 2000, and August 2001 were all taken to study several aspects of this ever-changing and extremely active Volcanic Field.

Tvashtar Catena has been pictured here just 10 months after both the NASA - Galileo and Cassini Spacecrafts observed the eruption of a Giant Plume of Volcanic Gases emanating from it. The plume rose some 385 Km (such as approx. 239 miles) high in the Sky and blanketed Terrains which were as far as about 700 Km (such as approx. 434,7 miles) from its center. Tvashtar has erupted in a variety of styles over the course of almost two years and we remember, in particular:

(1) a "Lava Curtain" approx. 50 Km (such as 31,5 miles) long in the Center Patera,

(2) a Giant Lava Flow (or "Lava Lake Eruption") in the Giant Patera at far left, and

(3) the very large Plume Eruption.

Given all the above, the Galileo Scientists expected that the Lava Flow Margins (or Patera Boundaries) within Tvashtar should have changed drastically, but this did not happen; as a matter of fact, the series of observations that were made revealed very little modifications of this sort, thus suggesting that the intense eruptions at Tvashtar were, in a way, "confined" by the Local Topography. North is towards the top of the mosaic, which is approximately 300 Km (such approx. 186,3 miles) across and has a resolution of 200 meters (656 feet) per picture element.

This picture (which is an Original NASA - Galileo Orbiter image mosaic published on the NASA - Planetary Photojournal with the ID n. PIA 03529) 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 Surface 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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