Summary: One of the main ingredients in the atmosphere of Titan, the largest moon of Saturn, is methane. The problem is, methane doesn’t hang around for long — it’s ripped apart by radiation from the Sun. That means that something must be replenishing the supply. There’s evidence that at least some of the methane could come from volcanoes. Not the kind we have on Earth, with towering columns of scalding ash and rivers of molten rock, but ice volcanoes. Titan’s surface is made mainly of water that’s frozen as hard as granite. But Saturn’s gravitational tug heats Titan’s interior, perhaps creating pools of slushy water mixed with ammonia and methane far below the surface. This mixture may force its way to the surface through cracks or weak spots in the ice, building cone-shaped mountains and perhaps releasing fresh methane into the atmosphere. One of the most likely ice volcanoes on Titan is known as Sotra Facula. It consists of two mountain peaks, the tallest of which is about a mile high. A frozen puddle on one side of the peaks looks like lava floes here on Earth. And the feature has a different chemical composition from the surface around it. Another region, Hotei Arcus, has shown significant changes over the last few years. While some researchers say the changes are most likely caused by blowing dunes, others interpret them as evidence of ongoing eruptions of an ice volcano — a source of fresh methane for Titan’s cold, thick atmosphere. Script by Damond Benningfield, Copyright 2012 This program was made possible in part by a grant from the NASA Science Mission Directorate For more skywatching tips, astronomy news, and much more, read StarDate magazine.
