Titan – Saturn’s Moon Saturn has the most complex and extensive system of satellites in the solar system as well as course as the rings.
There are 18 large moons as listed by Chaisson and McMillan in table 12 :2 Astronomy Today, 6th Edition page 322, which are usefully classed in 3 groups – the small moons which are irregularly shaped lumps of ice, each being less than 400 km in diameter. Their irregularities mean that they also exhibit irregularities in their motion. The second group are somewhat larger, being from 400km to 1500km in diameter. The third group has only one member – Titan, the second largest satellite in our solar system with a diameter of 5150km.
Only Jupiter’s moon Ganymede is larger. This makes it larger than both Mercury and Pluto.Titan has a dense atmosphere as was discovered by spectroscopic observation of its coloration and there has been scientific speculation that it could perhaps support life according to Chaisson and McMillan ( page 327) because now has conditions similar to those found on earth ,many millennia ago. They report ( page 323) that it was because astronomers were so keen to explore this idea that Voyager 1 was sent to pass as close as possible to it.
However the view from the spacecraft was totally obscured because of petrochemical reactions with light which cause the formation of a thick smog. The southern clouds are lighter in color than those in the northern hemisphere and there is also a dark cap over the northern pole area.Titan is 1,220,000 km from the planet’s surface and has a 16 day orbiting pattern. Its mass is 1.
83 when compared to the Earth’s moon mass, according to Chaisson and McMillan ( page 323) i.e. less than twice that of the Earth’s largest moon, a density of 1900 kg /m3 and 1.7 g/cm3 making it be far the densest of the major moons of Saturn.
Observations from Voyager 1 and from Cassini have been able to describe the atmosphere with accuracy as being made up of Nitrogen (N2) 90%, Argon ( Ar) up to 10 % and the tiny remainder is made up of methane and traces of other gases. Rachel Courtland, in New Scientist (September 2008),[1] comments that this is possibly similar to that of early Earth, which agrees with the comments of Chaisson and McMillan above. Because of the action of sunlight upon the various gases constant chemical reactions take place which between them maintain trace levels of hydrocarbon gas (H2) as well as Carbon Monoxide (CO), Ethane (C2H6) together with Propane (C3H8). The upper atmosphere is full of suspended droplets and the planet’s surface is apparently covered with organic material.
Methane, when combined with Nitrogen becomes Hydrogen Cyanide.As the Titan Saturn VI site[2] states this is important as from it amino acids can be built up. However because it has only a weak magnetic field, as on Mars, there is nothing to stop the atmosphere being stripped off into space by the power of solar winds. Its gravity is 1/7th of that enjoyed on Earth, but on the other hand the atmospheric pressure at ground level is 60% higher.
The atmosphere is protected to some extent , because for 95% of its time Titan is within the magnetosphere of Saturn itself. This has made it difficult for astronomers to study its own magnetic field, but even when it emerges briefly scientists report that for a period of 3 hours somehow the planet ‘remembers’ Saturn’s magnetic field. Courtland quotes Andrew Coates of University College London:-.[3] “Over long time scales, this could really help us understand how planetary atmospheres evolve.
“In August 2009 Saturns rings will appear edgewise as seen from Earth. Solar winds will then be reaching the moon’s surface from a different angle and will reverse the magnetic fields. Because of the massize atmosphere in comparison to its siz ethe winds have a huge impact, perhaps even rocking the moon on its axis according to Ralph Lorenz.[4] Scientists may then be able to at last determine, with the aid of Cassini data together with that obtained earlier the strength of the intrinsic magnetic field on Titan and from this suppose evidence about the planat’s interior including whether or not it has salty oceans on its surface.
In March 2008 Charles Choi[5] reported that the entire surface seems to be in constant motion. He reports that the recent Cassini-Huygens space mission revealed mountains coverd with ice and lakes of oil and seas that spurt both water and ammonia. Choi quotes Ralph Lorenz of the applied Physics Laboratory at John Hopkins University as saying:-Models of heat flow in Titan’s interior suggested years ago that Titan wouldlikely have an internal water or water-ammonia ocean…..
As we were mapping Titan’s surface, we were building maps up in little strips. Some of these strips overlapped, help tying the map together, but when you looked at where the features were in one strip compared with another strip, the coordinates weren’tthe same.The temperature is an icy -178C-289F, as might be expected because of the huge distance from the Sun. It is possible that close to the surface Methane and Ethane act as water does on Earth.
The shifts on the surface mean that there must be an ocean between it and the moon’s core.Lorenz believes that whether or not there ever was life on Titan the processes going on with its chemicals can teach us about how life began.Choi also quotes ASA Jet Propulsion Laboratory planetologist Christophe Sotin[6] who suggest that it will take another 6 years of careful observation in order to determine if there really is a subterranean ocean.;So it seems that the more that is found out about Titan the more there is to learn, and not just about life on a distant moon, but about life here on Earth.
;ReferencesElectronic SourcesChaisson, E and McMillan, S. Astronomy Today, 6th Edition, Pearson, Addison, Wesley, Boston 5th November 2008, http://wpscms.pearsoncmg.com/wps/media/objects/5879/6020712/ebook/at6ebk.
htmlChoi,C. Evidence for Ocean Found at Saturn’s Moon Titan, Space .com, March 2008, 5th November 2008 http://www.space.
com/scienceastronomy/080320-titan-ocean.htmlCourtland, R. Saturn magnetises its moon Titan, New Scientist, 11th September 2008, 5th November 2008 http://space.newscientist.
com/article/dn14717-saturn-magnetises-its-moon-titan.htmlHamilton, C, Titan, Saturn VI, 2007. 5th November 2008 http://www.solarviews.
com/eng/titan.htm[1] Courtland, R. Saturn magnetises its moon Titan, New Scientist, 11th September 2008, 5th November 2008 http://space.newscientist.
com/article/dn14717-saturn-magnetises-its-moon-titan.html[2] Hamilton, C, Titan, Saturn VI, 2007. 5th November 2008 http://www.solarviews.
com/eng/titan.htm[3] Courtland, R. Saturn magnetises its moon Titan, New Scientist, 11th September 2008, 5th November 2008 http://space.newscientist.
com/article/dn14717-saturn-magnetises-its-moon-titan.html[4] As quoted by Choi,C. Evidence for Ocean Found at Saturn’s Moon Titan, Space .com, March 2008, 5th November 2008 http://www.
space.com/scienceastronomy/080320-titan-ocean.html[5] Choi,C. Evidence for Ocean Found at Saturn’s Moon Titan, Space .
com, March 2008, 5th November 2008 http://www.space.com/scienceastronomy/080320-titan-ocean.html[6] Choi,C.
Evidence for Ocean Found at Saturn’s Moon Titan, Space .com, March 2008, 5th November 2008 http://www.space.com/scienceastronomy/080320-titan-ocean.html;
