NASAのインスタグラム(nasa) - 10月23日 19時29分

As southern winter solstice approaches in the Saturn system, NASA's Cassini spacecraft has been revealing dramatic seasonal changes in the atmospheric temperature and composition of Saturn's largest moon, Titan. Winter is taking a grip on Titan's southern hemisphere, and a strong, whirling atmospheric circulation pattern -- a vortex -- has developed in the upper atmosphere over the south pole. Cassini has observed that this vortex is enriched in trace gases -- gases that are otherwise quite rare in Titan's atmosphere. Cassini's observations show a reversal in the atmosphere above Titan's poles since the spacecraft arrived at Saturn in 2004, when similar features were seen in the northern hemisphere.

Images like this, from our Cassini spacecraft, lead scientists to conclude that the polar vortex clouds form at a much higher altitude -- where sunlight can still reach -- than the lower-altitude surrounding haze.

Credits: NASA/JPL-Caltech/Space Science Institute

#nasa #planet #astronomy #nasabeyond #cassini #saturn #titan #vortex #winter #science

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