Springtime on Saturn

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Credit: NASA/JPL/Space Science Institute

As the ringed planet's northern hemisphere enters spring, it becomes increasingly clear that its former blue tinge (see this image, for example), was the result of some winter process.

The blue top to the planet was a bit of a surprise when Cassini first arrived. No previous probe had observed this effect, and since it is further from the sun than the Earth, Saturn's winter hemisphere is always aimed away from our observatories on the ground, and concealed behind the rings.