A large mass of clouds swirls around the south pole of Titan, the largest moon of Saturn, in this view from the Saturn-orbiting Cassini spacecraft. A vortex has developed over the south pole as the season changes from winter to spring in Titan's southern hemisphere. Planetary scientists are expecting more changes in cloud and wind patterns as spring gives way to summer. [NASA/JPL/SSI]
It’s time for a change of seasons. Summer will arrive in the northern hemisphere tomorrow night. Over the coming weeks, temperatures will continue to warm north of the equator and cool south of it, causing changes to weather patterns across the entire planet.
The same thing happens on other planets and moons that have atmospheres. As one pole or the other nods more directly toward the Sun, the extra heat stirs up changes.
One example is Titan, the largest moon of Saturn. It has a cold, thick atmosphere made of nitrogen — the same element that makes up most of the atmosphere of Earth. Titan's atmosphere supports clouds of liquid methane and ethane, which may produce rain or drizzle.
In 2009, Saturn and its moons experienced an equinox, with their southern hemispheres starting to get most of the sunlight. That’s triggered a series of changes in Titan’s atmosphere.
The most obvious change has been at the poles. A vortex over the north pole has been disappearing, with a new one developing at the south pole. A layer of haze has been forming over the south pole as well, along with high-altitude clouds made of some type of ice. These changes are likely to accelerate as the southern hemisphere heads from spring to summer in the coming years.
And Saturn is in good view tonight. It looks like a bright star to the upper right of the Moon at nightfall. Saturn stays with the Moon as they swing across the southwest and set in the early morning.
Script by Damond Benningfield, Copyright 2013
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