The sulfur and various sulfuric compounds are responsible for the varying colors on Io's surface, giving it a mottled look. Other strange features of Io include lakes of molten sulfur, non-volcanic mountains, volcanic vents, and lava flows hundreds of miles long. It is similar to the way a coat hanger heats up when it is bent back and forth. The friction caused by this process creates a lot of heat within the small moon. This process distorts Io's surface by as much as 330 feet (100 meters). This "tug-of-war" is literally pulling the planet inside out. It is constantly being pulled by Europa and Ganymede, and then pulled back in its orbit by Jupiter. Astronomers believe that Io is caught in a process known as "tidal pumping". The most striking features are the volcanoes. It looks more like a pizza with "the works" than a moon. The surface of Io is covered by a number of strange features. It shows the unique and diverse landscape of this geologically active moon. This mosaic image of Io's surface was assembled from images acquired by the Voyager 1 and Galileo spacecraft. Io is the only body in the Solar System besides the Earth known to have active volcanoes. Observations with the Hubble Space telescope are constantly turning up new volcanic eruptions. Voyager sent back images of active volcanoes spewing sulfur hundreds of miles into space. Io's surface is littered with hundreds of volcanic calderas. The most surprising discovery on the Voyager mission was that of active volcanoes on Io. The surface is extremely young, and is constantly reshaping itself. Instead, they were shocked to find that Io has almost no craters. Astronomers had expected to see impact craters when the first pictures came in from the Voyager probes. Most of these features are believed to be formed by sulfur and sulfur compounds at different temperatures. The surface of this moon is pockmarked with more colors than could have been imagined. It is unlike any other moon in the Solar System. Io is without a doubt the most bizarre-looking object to be discovered by the Voyager spacecraft. Galileo close-up image of the Tupan Caldera volcano Galileo close-up image of Io showing volcanic activity Scientists think that the crater may, in some unknown way, be responsible for the large region of cold temperatures that surrounds it.Voyager 1 close-up of Io surface features The cold side includes the giant Herschel Crater, which is a few degrees warmer than its surroundings and so shows up in pink. Scientists think the cold part is colder because some kind of unidentified surface material on Mimas is allowing the Sun's energy to soak into the subsurface of the moon instead of only warming the surface, but why the transfer of heat varies so dramatically is still a big mystery. Typical temperatures on the warm part are near 92 K (-294 F), and typical temperatures on the cold part are near 77 K (-320 F). Instead of the smoothly changing temperatures that we see on most moons, Mimas is divided into a warm part (in yellow), and a cold part (in purple), with a sharp V-shaped boundary between them. To study this, they took infrared images of the surface, giving them a heat map of the moon. Astronomers were curious about the temperature patterns on the moon, and whether the crater would affect how Mimas is heated by the Sun. Looking at Mimas in visible light, there is a huge crater on the surface called Herschel crater. By splitting the light from Io using a spectrograph, astronomers were able to identify the molecular "fingerprints" of the sulfur and sulfur dioxide in the light.
IO MOON DIAMETER IN KM PATCH
A plume can be spotted in the upper right corner of the moon, in the same area as the bright hot patch in the infrared image to the lower right. Several of Io’s volcanoes produce plumes of sulfur and sulfur dioxide that climb as high as 500 km (300 mi) above the surface, and are easily seen in images like the one above. Infrared observations allow astronomers to easily pinpoint the volcanoes that are still active, allowing them to differentiate between current and old volcanic activity. Just as an elastic band warms up as you stretch it over and over again, the inside of Io heats up too, causing massive volcanic eruptions. Io's geologic activity is the result of “tidal heating” - the moon gets squeezed and stretched as it’s tugged around by the gravity of Jupiter and the other big moons, Europa, Ganymede, and Callisto.
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