NASA’s Cassini probe is nearing the end of its mission. The mission has enriched our understanding of Saturn and its moon. The extended mission and frequent visits to Titan have enabled scientists to observe the pattern of seasonal changes which occur on the biggest moon of the ringed planet. The spacecraft has revealed a reversal in the atmosphere over the Titan’s poles since 2004 when the spacecraft arrived at Saturn.
The probe has revealed that the southern hemisphere of the moon is in the grip of winter and there is a strong swirling atmospheric circulation pattern in the form of a vortex, which has developed over the South Pole.
The vortex is composed of trace gases which are otherwise quite rare in Titan’s atmosphere. Cassini observed that the features which are seen in the Southern Hemispheres was earlier seen in the Northern Hemisphere and the Vortex was formed over the North Pole when it visited Titan in 2004.
The craft arrived sometime in mid-northern winter, and now scientists have an opportunity to study the southern hemisphere winter. In other words, scientists have been able to explore the atmospheric conditions on Titan for two full seasons. Researchers have been able to understand the heat circulation which occurs as a pole-to-pole cycle of hot gases accumulating on the summer pole and cold gases subsiding at the winter pole.
There is a large scale reversal of the climate system starting immediately post-equinox in 2009.The moon’s hemispheres have responded according to varying seasonal changes. Winter has led to a fall of 40 degrees Celsius in the stratosphere above the South Pole in the last four years. This is in sharp contrast to the slow but steady warming in the Northern Hemispheres where temperatures remain relatively stable during early spring.