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Unexpected cooling effect in Saturn's upper atmosphere
January 29, 2007UK researchers from University College London (UCL), along with colleagues from Boston University, have found that the hotter than expected temperature of Saturn's upper atmosphere - and that of the other giant planets - is not due to the same mechanism that heats the atmosphere around the Earth's Northern Lights. Reporting in Nature (25th January) the researchers findings thus rule out a long held theory.
A simple calculation to give the expected temperature of a planet's upper atmosphere balances the amount of sunlight absorbed by the energy lost to the lower atmosphere. But the calculated values don't tally with the actual observations of the Gas Giants: they are consistently much hotter.
It has long been thought that the culprit behind the heating process was the ionosphere, being driven by the planet's magnetic field, or magnetosphere. By using numerical models of Saturn's atmosphere the researchers found that the net effects of the winds driven by polar energy inputs is not to heat the atmosphere but to actually cool it.
Professor Alan Aylward, of the UCL Department of Physics & Astronomy, and an author of the study, explains: "The aurora has been studied for over a hundred years, yet our discovery takes us back to first principles. We need to re-examine our basic assumptions about planetary atmospheres and what causes the observed heating."
"Studying what happens on planets such as Saturn gives us an insight into what happens closer to home. Planets can lose their atmospheres as we see with Mars. Do we completely understand how this happens? Are there mechanisms heating the gas and causing it to escape that we do not yet fully understand? By studying what happens in other atmospheres we may find clues to Earth's future."
Particle Physics & Astronomy Research Council
Professor Alan Aylward, of the UCL Department of Physics & Astronomy, and an author of the study, explains: "The aurora has been studied for over a hundred years, yet our discovery takes us back to first principles. We need to re-examine our basic assumptions about planetary atmospheres and what causes the observed heating."
"Studying what happens on planets such as Saturn gives us an insight into what happens closer to home. Planets can lose their atmospheres as we see with Mars. Do we completely understand how this happens? Are there mechanisms heating the gas and causing it to escape that we do not yet fully understand? By studying what happens in other atmospheres we may find clues to Earth's future."
Particle Physics & Astronomy Research Council
Upper Atmosphere Current Events and Upper Atmosphere News RSSNRL sensor provides critical space weather observations
Launched from Vandenberg Air Force Base, Calif., aboard an United Launch Alliance Atlas V launch vehicle, Oct. 18, 2009, the Special Sensor Ultraviolet Limb Imager (SSULI) developed by NRL's Space Science Division and Spacecraft Engineering Department offers a first of its kind technique for remote sensing of the ionosphere and thermosphere from space.
'Ultra-primitive' particles found in comet dust
Dust samples collected by high-flying aircraft in the upper atmosphere have yielded an unexpectedly rich trove of relicts from the ancient cosmos, report scientists from the Carnegie Institution.
NASA's Fermi Telescope Detects Gamma-Ray From
Nearby galaxies undergoing a furious pace of star formation also emit lots of gamma rays, say astronomers using NASA's Fermi Gamma-ray Space Telescope.
Switzerland has sent its first satellite into space
The Indian launcher Polar Space Launch Vehicle took off at 8:22 a.m. - Swiss time. Twenty minutes later, the SwissCube was ejected from the nose cone of the rocket at an altitude of around 720 kilometers.
Solar Cycle Driven by More than Sunspots; Sun Also Bombards Earth with High-Speed Streams of Wind
Challenging conventional wisdom, new research finds that the number of sunspots provides an incomplete measure of changes in the Sun's impact on Earth over the course of the 11-year solar cycle.
University of Toronto study shows climate change will lead to less ultraviolet radiation over northern high latitudes
Physicists at the University of Toronto have discovered that changes in the Earth's ozone layer due to climate change will reduce the amount of ultraviolet (UV) radiation in northern high latitude regions such as Siberia, Scandinavia and northern Canada.
Scientists discover surprise in Earth's upper atmosphere
UCLA atmospheric scientists have discovered a previously unknown basic mode of energy transfer from the solar wind to the Earth's magnetosphere. The research, federally funded by the National Science Foundation, could improve the safety and reliability of spacecraft that operate in the upper atmosphere.
Tropical storms endure over wet land, fizzle over dry
If it has already rained, it's going to continue to pour, according to a Purdue University study of how ocean-origin storms behave when they come ashore.
Tiny Flares Responsible for Outsized Heat of Sun's Atmosphere
"Why is the sun's corona so darned hot?" asks James Klimchuk, an astrophysicist at the Goddard Space Flight Center's Solar Physics Laboratory in Greenbelt, Md.
Global sunscreen won't save corals
Emergency plans to counteract global warming by artificially shading the Earth from incoming sunlight might lower the planet's temperature a few degrees, but such "geoengineering" solutions would do little to stop the acidification of the world oceans that threatens coral reefs and other marine life.
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