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Methane Found On Saturn Plays Crucial Role In Planet Formation
Using an infrared spectrometer on the Cassini-Huygens Spacecraft, researchers have measured the temperature, winds and chemical composition of Saturn, its rings and one of its moons, Phoebe.
The data appears in the Dec. 23 edition of "Science Express" and in the Dec. 24 print edition of Science.
Edward Wishnow of Lawrence Livermore National Laboratory participated in the research by measuring the spectrum of methane in the laboratory at temperatures and densities similar to the planet's–about 90 Kelvin (-297 degrees F) and one atmosphere of pressure.
Methane (CH4), the principal component of natural gas, is the main indicator of carbon on Saturn and Jupiter, and it plays a crucial role in the planet's atmospheric chemistry and history of formation.
The Cassini Composite Infrared Spectrometer (CIRS) is an infrared instrument that measures the intensity of far-infrared radiation, light with wavelengths between those of radar and near-infrared light.
These wavelengths are associated with radiation emission by the constituent gases of the planet's atmosphere or the ices and/or rocks that compose the rings and the moon Phoebe.
"Though we've known for years that the atmospheres of the giant planets are mainly made up of hydrogen and helium, using these instruments, we were able to measure the methane content with much greater precision than previous space missions," said Wishnow, who works in LLNL's Physics and Advanced Technologies Directorate.
The methane measurement shows that carbon is enriched on Saturn by seven times the amount found in the sun and two times the amount found on Jupiter, which is consistent with the rocky core hypothesis of giant planet formation.
In this model, Jupiter and Saturn began formation by accreting cores of about 10-12 times the size of Earth's mass of heavy elements, which, in turn, attracts the surrounding nebular gas in solar proportions.
Cassini-Huygens at JPL
Cassini Imaging Team
Lawrence Livermore National Laboratory
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Animation: Cassini's View Of Titan
Paris, France (ESA) Jan 05, 2005
Watch a fascinating animation showing Titan, Saturn's largest moon, as seen from the NASA/ESA/ASI Cassini spacecraft on 14 January 2005 during the time that ESA's Huygens probe is scheduled to descend through the moon's atmosphere.