Tuesday, April 20, 2010

Saturn’s Seasons Are Made in the Shade

The Cassini mission reports, Saturn’s Seasons Are Made in the Shade.

"Saturn's atmosphere is affected by seasonal changes just like Earth's is, but perhaps even more so, because the poles spend nearly 15 Earth-years in winter darkness and the next 15 years in sunlight. On top of that, the cooling shadow of the rings causes differences in heating and sunlight-driven chemistry between the shaded and sunlit parts of Saturn's atmosphere.

Cassini's years in orbit around Saturn have produced the first long-term space-based measurements of seasonal change on a gas-giant planet. In particular, Cassini's composite infrared spectrometer has recorded seasonal changes in Saturn's atmosphere, witnessing rapid responses in the atmospheric temperatures and hazes as the equinox approached last August. At that time, the incoming sunlight hit the rings edge-on, reducing the ring shadow to just a thin line across the planet's middle. Mission scientists have been struck by how quickly the atmosphere changed in response to the shifting ring shadow."

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