Astronomy Picture of the Day - powered by LUNEXIT.IT

The Zal Patera Region of Jupiter's Volcanic moon Io is shown in this combination of High and Low Resolution (HR and LR for short) images taken by the NASA - Galileo Spacecraft on July, 3, 1999 and on November 25, of the same year. By combining these two types of frames, the Galileo scientists were able to better understand the relationships existing between the different Minerals and Materials that characterize the entire Surface of Io and the underlying Geologic Structures. For example, in the center, toward the top of the picture, the Edge of the Zal Caldera (such as the Volcanic Crater) is marked by very dark (actually almost black) Flows, and it coincides with the Edge of a Plateau. Also, the dark brown/red Surface Material (visible just above and to the right of the upper central portion of the image and which fades in the Region located towards the lower portion of the frame) is typically associated with Active Volcanic Regions of Io (this meaning that the aforementioned Surface Material is found in places where Molten Lava is erupting onto the Surface). Here, the dark brown/red Surface Material follows the base of a Mountain: a fact which may also indicate, among other things, that Sulphurous Gases are being released and escaping along a Fault associated with the formation of the Mountain itself.

As you should remember, if we know the length that a shadow casts on a given Surface, as well as the Solar Incidence Angle relevant to the Area where the shadow is cast, we can estimate the height of the Relief projecting the shadow. In this case, we estimated that the Northernmost Plateau, which bounds the Western Edge of the Zal Patera, rises up to approximately 2 Km (6600 feet) high. The Mountain to the South of the Caldera, instead, has Peaks up to approximately 4,6 Km (such as about 15.000 feet) high, while the Small Peak visible near the bottom of the picture is approximately 4,2 Km (such as about 14.000 feet) high.

North is towards the top of the image, which is centered at 33,7° North Latitude and 81,9° West Longitude. The High Resolution images have a sharpness of about 260 meters (or yards) per picture element (---> Pixel), and they are illuminated from the left. These HR images were taken on November 25, 1999 from a distance of about 26.000 kilometers (16.000 miles) from the Surface of Io. The LR frames, on the other hand, are illuminated by the Sun that, at the moment the pictures were taken, was shining almost directly from behind the NASA - Galileo Spacecraft. The resolution of these LR images is approx. 1,3 Kilometers (such as about 0,8 miles) per Pixel and they were taken on July 3, 1999, from a distance of about 130.000 Kilometers (81.000 miles).

This frame has been colorized in Absolute Natural Colors (such as the colors that a human eye would actually perceive if someone were onboard the NASA - Galileo Spacecraft and then looked outside, towards the Jovian moon Io), by using an original technique created - and, in time, dramatically improved - by the Lunar Explorer Italia Team.