| Piú votate - Artistic Views of the Solar System |
En route to Titan.jpgHuygens Probe: en route to Titan118 visiteThe Huygens Probe, after deploying from the Cassini Orbiter, en route into the murky atmosphere of Saturn's largest moon, Titan.
(9 voti)
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Titan-PIA11001.jpgEthane Lake on Titan105 visiteNASA scientists have concluded that at least one of the large lakes observed on Saturn's moon Titan contains liquid hydrocarbons, and have positively identified the presence of ethane. This makes Titan the only body in our solar system beyond Earth known to have liquid on its surface.
Scientists made the discovery using data from an instrument aboard the Cassini spacecraft. The instrument identified chemically different materials based on the way they absorb and reflect infrared light. Before Cassini, scientists thought Titan would have global oceans of methane, ethane and other light hydrocarbons. More than 40 close flybys of Titan by Cassini show no such global oceans exist, but hundreds of dark, lake-like features are present. Until now, it was not known whether these features were liquid or simply dark, solid material.
"This is the first observation that really pins down that Titan has a surface lake filled with liquid," said Bob Brown of the University of Arizona, Tucson. Brown is the team leader of Cassini's visual and mapping instrument. The results will be published in the July 31 issue of the journal Nature.
Ethane and several other simple hydrocarbons have been identified in Titan's atmosphere, which consists of 95 percent nitrogen, with methane making up the other fiver percent. Ethane and other hydrocarbons are products from atmospheric chemistry caused by the breakdown of methane by sunlight.
Some of the hydrocarbons react further and form fine aerosol particles. All of these things in Titan's atmosphere make detecting and identifying materials on the surface difficult, because these particles form a ubiquitous hydrocarbon haze that hinders the view. Liquid ethane was identified using a technique that removed the interference from the atmospheric hydrocarbons.
The visual and mapping instrument observed a lake, Ontario Lacus, in Titan's south polar region during a close Cassini flyby in December 2007. The lake is roughly 20,000 square kilometers (7,800 square miles) in area, slightly larger than North America's Lake Ontario.
"Detection of liquid ethane confirms a long-held idea that lakes and seas filled with methane and ethane exist on Titan," said Larry Soderblom, a Cassini interdisciplinary scientist with the U.S. Geological Survey in Flagstaff, Ariz. "The fact we could detect the ethane spectral signatures of the lake even when it was so dimly illuminated, and at a slanted viewing path through Titan's atmosphere, raises expectations for exciting future lake discoveries by our instrument."
The ethane is in a liquid solution with methane, other hydrocarbons and nitrogen. At Titan's surface temperatures, approximately 300 degrees Fahrenheit below zero, these substances can exist as both liquid and gas. Titan shows overwhelming evidence of evaporation, rain, and fluid-carved channels draining into what, in this case, is a liquid hydrocarbon lake.
Earth has a hydrological cycle based on water and Titan has a cycle based on methane. Scientists ruled out the presence of water ice, ammonia, ammonia hydrate and carbon dioxide in Ontario Lacus. The observations also suggest the lake is evaporating. It is ringed by a dark beach, where the black lake merges with the bright shoreline. Cassini also observed a shelf and beach being exposed as the lake evaporates. "During the next few years, the vast array of lakes and seas on Titan's north pole mapped with Cassini's radar instrument will emerge from polar darkness into sunlight, giving the infrared instrument rich opportunities to watch for seasonal changes of Titan's lakes," Soderblom said.
More information is available at: http://www.nasa.gov/cassini, http://saturn.jpl.nasa.gov and http://wwwvims.lpl.arizona.edu .
MareKromium
(8 voti)
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Martian_Residual_Lake-2779-22384.jpgResidual Lake on Mars71 visitenessun commentoMareKromium
(7 voti)
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UB-313.jpgUB 313: is this the "10th Planet"?76 visiteWhat do you call an outer Solar System object that is larger than Pluto? Nobody is yet sure, but the question arose recently when 2003 UB313, an object currently twice as far out as Pluto and not in the plane with the rest of the Planets, was verified recently to be 30% wider than Pluto. UB313's size was estimated (of course in a VERY approximate way!) by measuring how much infrared light this celestial body emits. Previous size estimates were based only on visible light and greatly affected by how reflective the object is.
Whether 2003 UB313 is officially declared a planet will be answered shortly by the International Astronomical Union (IAU).
In the above picture, a scientific artist has imagined UB313 in its distant orbit around the Sun, coupled with a hypothetical moon.
(7 voti)
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Unknown_Centaur.JPGUnknown Centaur75 visitenessun commentoMareKromium
(6 voti)
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Venus-Lightning.jpgVenusian Lightnings63 visiteCaption ESA:"This artist’s concept of Venus, dated 2006, suggests the presence of lightning in the atmosphere". MareKromium
(6 voti)
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The_Rings-PIA10082.jpgMittens64 visiteCaption NASA:"This is an artist concept of the view from Cassini during the star occultation that detected "Mittens," the small object to the right of the star. As Cassini watched the star pass behind Saturn's F-Ring (foreground), the star blinked out when Mittens blocked it, indicating it may be a solid moonlet".MareKromium
(6 voti)
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The_Rings-PIA10081.jpgIcy Rings66 visiteCaption NASA:"This is an artist concept of a close-up view of Saturn's Ring particles. The planet Saturn is seen in the background (yellow and brown).
The particles (blue) are composed mostly of ice, but are not uniform. They clump together to form elongated, curved aggregates, continually forming and dispersing. The space between the clumps is mostly empty. The largest individual particles shown are a few meters (yards) across". MareKromium
(6 voti)
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Enceladus~2.jpgEnceladian Geysers123 visiteDa "NASA - Picture of the Day" dell'8 Giugno 2006:"In this stunning Saturnian vista - one in a series of artist's visions of volcanos on alien worlds - icy geysers erupt along narrow fractures in inner moon Enceladus. The majestic plumes were actually discovered by instruments on the Cassini Spacecraft during close encounters with bright and shiny Enceladus last year. Researchers now suspect the plumes originate from near-surface pockets of liquid water with temperatures near 273 kelvins (0° Celsius) - hot when compared to the distant moon's surface temperature of 73 kelvins (- 200° C). A dramatic sign that tiny, 500km-diameter Enceladus is surprisingly active, these ice volcanos hold out another potential site in the search for water and origin of life beyond planet Earth.
Enceladus' ice volcanos also likely produce Saturn's faint but extended E-Ring".
(6 voti)
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Volcanoes-Olympus_and_Clouds.jpgOlympus, in a Sea of Clouds (Painting by Gordon Legg, based on Viking Orbiter mosaic P17444. From NASA SP-444, 1980) 127 visiteThis painting, based on a mosaic of black-and-white Viking Orbiter images of Olympus Mons, shows the volcano's flanks and complex caldera protruding above thin clouds of water ice. MareKromium
(5 voti)
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Earth___Moon-Galileo.jpgThe Earth-Moon System93 visiteCaption NASA originale:"A double planet? From 6,4 MKM away on December 16, 1992, NASA's Robot Spacecraft Galileo took this picture of the Earth-Moon System. The bright, sunlit half of the Earth contrasts strongly with the darker subdued colors of the Moon.
Our Moon is one of the largest moons in the Solar System. It is even larger than the planet Pluto. In this picture, the Earth-moon system actually appears to be a double planet".
(5 voti)
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Bardarbunga.jpgBardarbunga256 visiteMother Earth when is pissed...
And, please, do not confuse this funny-named Icelandic Volcano with the Italian "Bunga-Bunga" dance (or party)...MareKromium
(4 voti)
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