Titan when the sun goes red giant ?

killium · Feb 13, 2008

It is said that Titan is like a frozen, pre-biotic, earth. So what happens if it is suddenly heated up ? When the sun will go into red giant phase, will Titan get more heat since it will be closer (relatively) ? <div class="Discussion_UserSignature"> </div>

Saiph · Feb 14, 2008

Titan will get warmer during that stage, as the sun is more luminous, even if the surface temperature is cooler. The specifics elude me at the moment, and I don't feel like cranking through the math. But there are several possible scenarios: The moon thaws, and maintains it's atmosphere, it remains frozen, or it thaws, but the increased influx of light also strips it of it's surface volatiles...i.e. it dries out. <div class="Discussion_UserSignature"> --------------------SaiphMOD@gmail.com -------------------"This is my Timey Wimey Detector. Goes "bing" when there's stuff. It also fries eggs at 30 paces, wether you want it to or not actually. I've learned to stay away from hens: It's not pretty when they blow" -- The Tenth Doctor, "Blink" </div>

venator_3000 · Feb 14, 2008

Hmm, that's an interesting question. To engage in fantasy let's assume that several billion years from now the Sun balloons outward. Anyone remember the Bonesteel painting where it shows the last day on Earth in just such a scenario? In one lower corner there is a little human skeleton clinging to rocks in what looks like a hades. So, with this image in mind I will assume that when the event occurs people don't live on Titan. If people don't live on Titan and it remains unchanged then the expansion of the Sun in this phase means that Titan warms up. Chemical changes occur. This could prompt life to develop on Titan. Such life might be tenuous. It would enjoy this flowering of Titan until the Sun's continued expansion makes the new Eden uninhabitable. Perhaps native Titanian life is already there or perhaps the Huygens probe, despite precautions, deposited some bacteria there that is waiting and dormant until this event occurs. In this scenario I also imagine the book 2010 where intelligence evolves thanks to conditions that change in the Jovian system. On Titan, with the ballooning Sun, it of course still orbits Saturn although maybe Saturn loses some or all of the rings. Under these skies, cribbing a page from Mr. Clarke, intelligence evolves. Either it is native to Titan or something we accidently leave there. But the solar expansion is a double edged sword. Sentience evolves thanks to the expanded Sun, but that same Sun will eventually gobble everything up. Our Titanians would need to leave for other stars or resign themselves to their fate. That's my scenario, anyway. v3k <div class="Discussion_UserSignature"> </div>

Mee_n_Mac · Feb 14, 2008

I don't know that the red giant Sun will enventually gobble everything up. I thought it was expected to balloon out to about the Earth's present orbit. Mercury is gone and maybe Venus as well. Earth becomes a molten slagball. Remember that some of the Sun's mass is lost when it huffs and puffs and so the planets orbits will move outward some. Whether the new orbit and Sun's intensity put Titan in a habitable zone is a calculation I can't do. <div class="Discussion_UserSignature"> -----------------------------------------------------Ask not what your Forum Software can do do on you,Ask it to, please for the love of all that's Holy, STOP ! </div>

3488 · Feb 14, 2008

I suspect that the Red Giant sun will strip Titan of its volatiles & Titan ends up as a larger version of our Moon. During the initial Red Giant phase our Sun will turn into a star, not too different to either Arcturus / Alpha Bootis or Aldebaran / Alpha Tauri, approx 40 times wider & 140 times more powerful than the current Sun. So the Saturn system at the moment receives approx 10 watts per metre square metre. In the initial red giant phase, the Saturn system will receive approx 1,400 watts per square metre, a little stronger than Earth receives right now. What would happen to Titan if we moved it to just inside Earth's orbit? Titan's surface gravity is 14.1% of Earth's, that is weaker than the Moon's 16.7%. My guess is that Titan will dry out & be a large moon like object, rocky & airless. 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>

3488 · Feb 14, 2008

Hi Mee_n_Mac. Yes after the initial red giant phase, the Sun will balloon to about the approximate current orbit of the Earth. The Earth is likely to recede somewhat, but even allowing for that, the Earth will become a ball of molten rock & metal. Allowing for the fact that Saturn too will likely recede, the red Supergiant phase of the Sun will still reduce Titan to a moon like object. During this phase even objects like the KBOs Eris & Pluto are likely to lose a lot of volatiles. So I think Titan is a no hoper during this phase. 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>

venator_3000 · Feb 14, 2008

Hmmm...did I say gobble? Well, most assumptions I've read suggest the Sun's red giant phase could see expansion 50 - 200 times its current diameter. But then I thought about your statement and put some numbers around what that means... So for my answer this time I'll do a little math. Sun's diameter: 1.4 x 10^6 km Current Saturn-Sun distance: 9.8 AU where 1 AU = 150,000,000 km (approximate) so distance to Saturn from the Sun = 1,470,000,000 km. If I consider a red-giant phase expansion of 200x then the solar diameter becomes 280,000,000 km If I consider a red-giant phase expansion of 100x then the solar diameter becomes 140,000,000 km If I consider a red-giant phase expansion of 50x then the solar diameter becomes 70,000,000 km Then, assuming Saturn's distance remains the same: Distance from expanded Sun to Saturn: 50x scenario: 1,400,000,000 km 100x scenario: 1,435,000,000 km 200x scenario: 1,330,000,000 km So, the change we see is not actually a gobble but a minor warming!!! As the Sun expands it will also lose mass. This could cause the orbits of the planets to change. But allow me to assume Saturn's orbit doesn't change (big assumption). But for convenience I'll keep that 9.8 AU distance for Titan and look at heat flux. Using the inverse square law I'll be basing my calculation on current earth-normal flux (1370 watts / m^2) falls on Earth from the Sun. Saturn, in the 200x expansion scenario, is 1,330,000,000 or about 8.8 AU from the Sun. 8.8 AU is 8.8 TIMES the current Earth-Sun distance. Using inverse-square law the solar flux is (Intensity at Earth) / (Distance squared) as derived from I=S/4(pi)r^2 So, I = 1370 / (8.8)^2 = 1370 / 78.6 = 17.5 watts per m^2! In the other scenarios the heating is less. Of course, I do not have a value for S if the sun is a red giant, only the S value as the <div class="Discussion_UserSignature"> </div>

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