In Saturn's Atmosphere....

l3p3r · Oct 25, 2008

Hi all, I've been curious about this for a long time; how deep would you have to go into Saturn's atmosphere to reach one Earth atm. pressure? Would you be below thick cloud cover (i.e. not able to see the stars at night?) and what might the temperature be there? cheers <div class="Discussion_UserSignature"> </div>

MeteorWayne · Oct 25, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'>Hi all, I've been curious about this for a long time; how deep would you have to go into Saturn's atmosphere to reach one Earth atm. pressure? Would you be below thick cloud cover (i.e. not able to see the stars at night?) and what might the temperature be there? cheers Posted by l3p3r</DIV> The better way to phrase the question is how far from the center is that layer. The reason is, it's impossible to define the outer edge of an atmosphere. For example, on earth the troposphere (where all the weather takes place) extends to about 10 miles (16 km), yet there's enough atmosphere at 100 km (60 miles) to cause meteors to burn up, and even at the orbital height of the ISS ~ 350 km, there's enough atmosphere to cause the ISS to slowly lose altitude, requiring periodic reboosts. In general, the radius fgures give for Saturn are measured to exactly the point you asked about, or 1 bar (1 earth surace atmospheric pressure)<table border="0" cellspacing="2" class="infobox vcard" style="font-size:90%;width:20em;text-align:left"><tbody><tr><th style="line-height:1.1em">Equatorial radius</th><td style="line-height:1.2em">60,268 ± 4 km 9.4492 Earths

baulten · Oct 25, 2008

I don't know about Saturn, but on Jupiter, it's pretty cold at 1 atm, and at ~20 C it's something like 9 atm, I think.  Saturn probably has a bigger varience, seeing as it's smaller (radiates less heat) and further from the sun.

3488 · Oct 26, 2008

At approx 1.2 Earth atmospheres (1,200 mb), the temperature of Saturn's atmosphere s -130 C / 143 K.At approx 1 Bar (1 Earth Atmosphere, 1,000 mb) the temperature is -135 C / 138 K. At the 70 mb level, Saturn's Tropopause, the lowest temperatures of -191 C / 82 K have been deduced.  Replying to: <DIV CLASS='Discussion_PostQuote'>I don't know about Saturn, but on Jupiter, it's pretty cold at 1 atm, and at ~20 C it's something like 9 atm, I think.  Saturn probably has a bigger varience, seeing as it's smaller (radiates less heat) and further from the sun. Posted by baulten</DIV>Hi baulten, that's very true.At 1 Bar in Jupiter's atmosphere, the temperature is -105 C / 168 K. 30 degrees C / K warmer than Saturn's, but still pretty cold by terrestrial standards.At the 0.1 Bar (100 mb) level, Jupiter's tropopause, the lowest temperatures have been found at approx -163 C / 110 K.At approx 150 KM below the 1 Bar level, at 22 Bars, the Galileo Spacecraft entry probe measured a temp of 153 C / 426 K. Also worth remembering, Jupiter's atmosphere is denser but shallower than Saturn's due to Jupiter's much greater gravity (2.65 Earth's at the 1 Bar level, as against Saturn's 1.14 Earth's at the same level).Also Jupiter is still releasing heat through contraction as well as releasing fossil accretion heat, where as with Saturn, contraction has long since ceased, most if not all accretional heat has also been released & most of Saturn's excesive heat is due to the Helium separating out from the hydrogen, releasing heat. With Jupiter, this has not yet started. Andrew Brown. <div class="Discussion_UserSignature"> "I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before". Linda Morabito on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.http://www.launchphotography.com/ http://anthmartian.googlepages.com/thisislandearthhttp://web.me.com/meridianijournal </div>

l3p3r · Oct 28, 2008

Wow great answers guys thanks!! I was just curious about the possibility of setting up some sort of holiday blimp in the Saturnian atmosphere at 1bar.. but it seems to be a bit cold!  Andrew, might I also ask what the difference is between heat from contraction and accretional heat? Also; why has Saturn's contraction ceased and Jupiters has not?  Thanks! <div class="Discussion_UserSignature"> </div>

3488 · Oct 28, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'>Wow great answers guys thanks!! I was just curious about the possibility of setting up some sort of holiday blimp in the Saturnian atmosphere at 1bar.. but it seems to be a bit cold!  Andrew, might I also ask what the difference is between heat from contraction and accretional heat? Also; why has Saturn's contraction ceased and Jupiters has not?  Thanks! Posted by l3p3r</DIV>Hi I3p3r,Firstly you are very welcome, that is why we are here. It's a bit too chilly IMO to have a holiday blimp at the 1 Bar level in either atmosphere.With Uranus & Neptune, its even worse, at the 1 Bar levels. -216 C / 57 K for Uranus & -200 C / 73 K for Neptune. Neptune's is warmer due to Neptune having greater excessive heat than Uranus, despite being nearly twice as far from the Sun.At the tropopause of Uranus the temperature drops to -221 C / 52 K & at the tropopause of Neptune drops to -223 C / 50 K. This very small difference between the two is also symptomatic of Neptune having a far greater excess heat than Uranus. Accretional Heat was generated when the planets actually formed, the energy created when the planets actually grew & gained mass.With Jupiter, so much accretional heat was generated that it can be seen in the density profiles of the Galilean moons. Io, the densest moon in the Solar System, mostly rock & metal. Did not capture much in the way of low temperature volatiles as Jupiter itself was so hot that it may have been more like a brown dwarf failed star (though Jupiter is not massive enough to be a true brown dwarf, may certainly have mimicked one it its youth). Europa, further out also fairly dense (third densest moon in solar system behind Io & our own Moon) but has an ice crust (possibly sub surface ocean), so was far enough away to retain some low temperature volatiles, though still only a tiny amount as compared to the mass of the whole body.Ganymede (solar system's largest moon), further out still, less dense again, more ice, in fact much more ice (perhaps two thirds rock & one third ice ) than Europa. Callisto (solar system's third largest moon), further out & less dense still, perhaps half rock & half ice.The tailing off of density of these four large moons as distance increases from Jupiter is evidence of Jupiter's immense accretional heat in its youth. The further out, the more ice & low temperature volatiles could remain without being driven off. Jupiter still with a mass of 318 Earths is still releasing some accretional heat from those early days. Also Jupiter is still contracting, very slowly, approx 1mm per century, but is enough to release further heat.Saturn on the other hand being far less massive at 'only' 95 times Earth masses, has already lost the accretional heat & even that was only a fraction of Jupiter's as Saturn's moons show no such tailing off with densities, look at Mimas, an ice ball, very close in & other smaller icy moons even closer in. Also Saturn does not appear to be contracting either, but the excess heat is from the differentiation of the heavier helium raining out from the lighter hydrogen, thus releasing heat & driving the extreme weather in Saturn's atmosphere.Hope that helps.Andrew Brown.  <div class="Discussion_UserSignature"> "I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before". Linda Morabito on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.http://www.launchphotography.com/ http://anthmartian.googlepages.com/thisislandearthhttp://web.me.com/meridianijournal </div>

UFmbutler · Oct 29, 2008

I'd just like to point out that the community is still unsure whether Jupiter's formation was due to the Core Accretion model, the thing 3488 is talking about, or the Disk Instability model, or a combination of both.  I personally believe the evidence of Jupiter having a rocky core is convincing, but there are still some people who don't believe it. I may have misunderstood your point though...by accretion do you mean what it standardly means(i.e., the accretion of dust grains and ices) or just the general accretion of gases?  I guess the formation doesn't really matter for your point, since we are talking about how it is contracting now, but I just thought I'd point out that there is still some controversy about this topic. <div class="Discussion_UserSignature"> </div>

3488 · Oct 29, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'>I'd just like to point out that the community is still unsure whether Jupiter's formation was due to the Core Accretion model, the thing 3488 is talking about, or the Disk Instability model, or a combination of both.  I personally believe the evidence of Jupiter having a rocky core is convincing, but there are still some people who don't believe it. I may have misunderstood your point though...by accretion do you mean what it standardly means(i.e., the accretion of dust grains and ices) or just the general accretion of gases?  I guess the formation doesn't really matter for your point, since we are talking about how it is contracting now, but I just thought I'd point out that there is still some controversy about this topic. Posted by UFmbutler</DIV>Hi UFmbutler,You can call me Andrew. Yes IMO only but as you say, there is a huge difference of opinion regarding Jupiter's formation.Myself, I think that Jupiter started off as a giant accumulation of dust & ices forming the core. As temperatures were very low, comets & ice rich asteroids were in abundance, the protosun had not as yet began thermonuclear reactions, this ice & rock core was able to sweep up & accumulate a huge annulus of hydrogen within the protoplanetary disk & Jupiter formed very quickly, maybe over a period of only a few million years. So to me the Core Accretion Model so far appears to be the most attractive scenario. It's difficult to know for sure without higher resolution global gravity data. Perhaps this is something that the JUNO mission may help solve.The gas accretion model suggests that Jupiter is in fact a failed star, became depleted of material at about it's current mass, perhaps was on the way to becoming the Sun's binary companion. The Galileo mission, both orbiter & entry probe, as well as Pioneers 10 & 11 & Voyagers 1 & 2 that came before did not rule out either scenario, but somehow I favour the Core Accretion Model. Andrew Brown.  <div class="Discussion_UserSignature"> "I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before". Linda Morabito on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.http://www.launchphotography.com/ http://anthmartian.googlepages.com/thisislandearthhttp://web.me.com/meridianijournal </div>

marsbug · Nov 5, 2008

I have read that the temperatures for liquid water are reached at the 5 bar point in jupiters atmosphere, and around the twenty bar point in saturns. Water condensation is theorized to play an important role in both atmospheres, so at the right levels it might be available to drink. If humans can adjust to 5 bars of pressure, which doesn't seem that unreasonable (I remember hearing that deep sea divers work under that kind of pressure), the manned airship idea could still work, although anyone outside would probably still have to wear an oxygen mask.I'd like to see more interest in jupiter and saturn themselves. Too often they get overshadowed by the possibility of sea or oceans on their moons. The weather systems that both worlds host are interesting in themselves and still only half understood. Important questions remain, like: why is the great red spot red,  how deep do the storms and weather systems extend, why do some storms last for centuries and reach great size and others for only for days, why are jupiters large storms dominated by anticyclone and earth by cyclones, which is more important in powering the storms: heat from below or absorbing other storms, what is forming the polar hexagon on saturn, etc..... Some of the questions are answered by theories, but these theories need confirming, and some are still very mysterious. And understanding weather on the gas and ice giants is directly relavant to better understanding of weather here on earth... so up with jupiter and saturn, down with europa and titan!

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In Saturn's Atmosphere....

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