The fate of the Earth?
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From: Yousuf Khan on 3 Sep 2009 01:55 mike3 wrote: > Hi. > > I saw this discussion: > http://www.sciforums.com/archive/index.php/t-41880.html > > One poster posted: > "Well I'm about to finish the book on that. Venus has stopped spinning > by an internal mechanism that was feeded by chaotic resonance in its > orbit. Consequently the planet heated up tremendously melting it > completely. This happened one to two billion years ago. We still see > the residual heat of that process and this has nothing to do with > greenhouse gas effect. > > There are many details supporting that hypothesis, like the shaping > and geologic frequencies of the plains indicating melting, the > exponential declining of volcanic activity indicates strong cooling > etc. The new paradigm rthat is currently emerging is "radiogenic heat" > and a lot of it. But what is the source. The most likely element - > potassium40- (40K) is also much more rare on Venus? > > It was the big brake." > > Is any of this good theory? If so, what sort of implication would it > have for the far future of the Earth, when the Sun's luminosity > increases to the point it begins to evaporate the oceans from the > globe? (Note that this happens quite far in advance of the red giant > phase.) As it seems to suggest things other than greenhouse are > necessary to get the Venus-like environment. If melting it down is > required to keep it so hot, not just greenhouse, then could it be that > the Earth might instead of becoming like Venus become more like Mars > with a depleted, thin and wispy atmosphere? Or is this bad theory? > It's been about 5 years since this was posted, so I suppose more work > has been done now on this subject. > No, I don't think it's good theory. The Venus greenhouse was caused by a lack of magnetic field. The lack of magnetic field was caused by Venus' lack of rotation. Venus' lack of rotation was caused by god-knows-what. I don't think there is any good theory as to what caused Venus to stop spinning, although the favourite theory seems to suggest a resonance with Jupiter caused it. But that doesn't explain why Earth and Mars weren't affected, but why Mercury and Venus might have been. Regarding Earth's greenhouse fate in the future. It's been suggested that within 1 billion years, the Sun will be 10% hotter than it is today, rendering habitation on Earth impossible. That ignores the fact that the Sun was 10% cooler, 1 billion years ago too. The Earth adjusted to the cooler Sun then, and it may very well adjust to the warmer Sun. Certain theories suggest that lifeforms on Earth itself alter the atmosphere enough to keep the planet habitable. Yousuf Khan
From: Sam Wormley on 3 Sep 2009 02:09 Yousuf Khan wrote: > > I don't think there is any good theory as to what caused Venus to stop > spinning, although the favourite theory seems to suggest a resonance > with Jupiter caused it. But that doesn't explain why Earth and Mars > weren't affected, but why Mercury and Venus might have been. > http://en.wikipedia.org/wiki/Venus#Orbit_and_rotation http://www.agu.org/pubs/crossref/2005/2003JE002190.shtml
From: BradGuth on 3 Sep 2009 02:37 On Sep 2, 8:08 pm, mike3 <mike4...(a)yahoo.com> wrote: > Hi. > > I saw this discussion:http://www.sciforums.com/archive/index.php/t-41880.html > > One poster posted: > "Well I'm about to finish the book on that. Venus has stopped spinning > by an internal mechanism that was feeded by chaotic resonance in its > orbit. Consequently the planet heated up tremendously melting it > completely. This happened one to two billion years ago. We still see > the residual heat of that process and this has nothing to do with > greenhouse gas effect. > > There are many details supporting that hypothesis, like the shaping > and geologic frequencies of the plains indicating melting, the > exponential declining of volcanic activity indicates strong cooling > etc. The new paradigm rthat is currently emerging is "radiogenic heat" > and a lot of it. But what is the source. The most likely element - > potassium40- (40K) is also much more rare on Venus? > > It was the big brake." > > Is any of this good theory? If so, what sort of implication would it > have for the far future of the Earth, when the Sun's luminosity > increases to the point it begins to evaporate the oceans from the > globe? (Note that this happens quite far in advance of the red giant > phase.) As it seems to suggest things other than greenhouse are > necessary to get the Venus-like environment. If melting it down is > required to keep it so hot, not just greenhouse, then could it be that > the Earth might instead of becoming like Venus become more like Mars > with a depleted, thin and wispy atmosphere? Or is this bad theory? > It's been about 5 years since this was posted, so I suppose more work > has been done now on this subject. Simple, planet Venus isn't as old as Earth, and Venus somehow lost its big old moon (could have been Mercury). ~ BG
From: alien8er on 3 Sep 2009 02:39 On Sep 2, 10:55 pm, Yousuf Khan <bbb...(a)yahoo.com> wrote: > mike3 wrote: > > Hi. > > > I saw this discussion: > >http://www.sciforums.com/archive/index.php/t-41880.html > > > One poster posted: > > "Well I'm about to finish the book on that. Venus has stopped spinning > > by an internal mechanism that was feeded by chaotic resonance in its > > orbit. Consequently the planet heated up tremendously melting it > > completely. This happened one to two billion years ago. We still see > > the residual heat of that process and this has nothing to do with > > greenhouse gas effect. > > > There are many details supporting that hypothesis, like the shaping > > and geologic frequencies of the plains indicating melting, the > > exponential declining of volcanic activity indicates strong cooling > > etc. The new paradigm rthat is currently emerging is "radiogenic heat" > > and a lot of it. But what is the source. The most likely element - > > potassium40- (40K) is also much more rare on Venus? > > > It was the big brake." > > > Is any of this good theory? If so, what sort of implication would it > > have for the far future of the Earth, when the Sun's luminosity > > increases to the point it begins to evaporate the oceans from the > > globe? (Note that this happens quite far in advance of the red giant > > phase.) As it seems to suggest things other than greenhouse are > > necessary to get the Venus-like environment. If melting it down is > > required to keep it so hot, not just greenhouse, then could it be that > > the Earth might instead of becoming like Venus become more like Mars > > with a depleted, thin and wispy atmosphere? Or is this bad theory? > > It's been about 5 years since this was posted, so I suppose more work > > has been done now on this subject. > > No, I don't think it's good theory. The Venus greenhouse was caused by a > lack of magnetic field. The lack of magnetic field was caused by Venus' > lack of rotation. Venus' lack of rotation was caused by god-knows-what. I think you have that slightly sideways; as I understand it the greenhouse stopped plate tectonics, vulcanism, and the core circulation that creates a planetary magnetic field by eliminating (well, strongly suppressing) the usual temperature differential between the core and the surface. But I agree the "theory" doesn't sound right either. > I don't think there is any good theory as to what caused Venus to stop > spinning, although the favourite theory seems to suggest a resonance > with Jupiter caused it. But that doesn't explain why Earth and Mars > weren't affected, but why Mercury and Venus might have been. Worse, neither Venus nor Earth have large mascons like Earth's moon and Mars do. OTOH Venus' orbit is the most nearly perfectly circular of all the planets. Since there are two glaring anomalies there, no spin and a nearly perfectly circular orbit, it wold seem there's a connection, but it sure isn't obvious. > Regarding Earth's greenhouse fate in the future. It's been suggested > that within 1 billion years, the Sun will be 10% hotter than it is > today, rendering habitation on Earth impossible. That ignores the fact > that the Sun was 10% cooler, 1 billion years ago too. The Earth adjusted > to the cooler Sun then, and it may very well adjust to the warmer Sun. > Certain theories suggest that lifeforms on Earth itself alter the > atmosphere enough to keep the planet habitable. But then the Earth is also slowly fleeing the sun as its orbital energy radiates away as (theoretical) gravitons. Different timescales for all these processes though, and life can only do so much if the sun gets bright enough to compensate for the increasing distance. Mark L. Fergerson
From: YKhan on 3 Sep 2009 12:00
On Sep 3, 2:39 am, alien8er <alien8...(a)gmail.com> wrote: > On Sep 2, 10:55 pm, Yousuf Khan <bbb...(a)yahoo.com> wrote: > > No, I don't think it's good theory. The Venus greenhouse was caused by a > > lack of magnetic field. The lack of magnetic field was caused by Venus' > > lack of rotation. Venus' lack of rotation was caused by god-knows-what. > > I think you have that slightly sideways; as I understand it the > greenhouse stopped plate tectonics, vulcanism, and the core > circulation that creates a planetary magnetic field by eliminating > (well, strongly suppressing) the usual temperature differential > between the core and the surface. The temperature at the surface of Venus is still nothing compared to the temperature at the core. The Earth's core temperature is estimated at between 5000-7000K, which would be presumably the estimate for Venus' core temperature since they are of nearly the same mass. Venus' surface temperature is only 750K. Besides, it's highly unlikely that the atmosphere has enough power to stop plate tectonics. It's not even clear if plate tectonics on Venus has actually stopped as there seems to be volcanos on Venus, some of which may or may not be active. > > I don't think there is any good theory as to what caused Venus to stop > > spinning, although the favourite theory seems to suggest a resonance > > with Jupiter caused it. But that doesn't explain why Earth and Mars > > weren't affected, but why Mercury and Venus might have been. > > Worse, neither Venus nor Earth have large mascons like Earth's moon > and Mars do. I'll assume you were comparing Venus and _Mercury_ against Earth and Mars. Mars' moons are nothing more than captured asteroids. They aren't big enough to affect Mars' rotation. Mars' moons would actually look insignificant next to Earth's Moon, and they could in fact easily orbit the Moon as its own moons. Phobos, the biggest one, is only on average 22 km in diameter, whereas the Moon is 3500 km. Mars diameter is 6800 km, and Earth is 12800 km. This one shows the relative size of the Moon versus the rocky planets (but doesn't show Phobos or Deimos): http://www.saintjoe.edu/~dept14/environment/rogero/core5/solar_systems01.jpg > OTOH Venus' orbit is the most nearly perfectly circular of all the > planets. Since there are two glaring anomalies there, no spin and a > nearly perfectly circular orbit, it wold seem there's a connection, > but it sure isn't obvious. Here's a size comparison of what the Sun looks like at aphelion vs. perihelion from Earth. Astrophotography by Anthony Ayiomamitis http://www.perseus.gr/Astro-Solar-Scenes-Aph-Perihelion.htm > > Regarding Earth's greenhouse fate in the future. It's been suggested > > that within 1 billion years, the Sun will be 10% hotter than it is > > today, rendering habitation on Earth impossible. That ignores the fact > > that the Sun was 10% cooler, 1 billion years ago too. The Earth adjusted > > to the cooler Sun then, and it may very well adjust to the warmer Sun. > > Certain theories suggest that lifeforms on Earth itself alter the > > atmosphere enough to keep the planet habitable. > > But then the Earth is also slowly fleeing the sun as its orbital > energy radiates away as (theoretical) gravitons. That's not happening. The Earth won't move away from the Sun until the Sun loses a significant amount of its mass, when it goes into its red giant phase. The Sun might puff out a large amount of matter as a planetary nebula at that point, and it would thus reduce in mass, thus Earth would move away from it. But losses due to gravitational friction don't happen until the two bodies are significantly closer to each other. And those energy losses would result in the Earth getting closer not further away. > Different timescales for all these processes though, and life can > only do so much if the sun gets bright enough to compensate for the > increasing distance. Life has already completely changed the entire composition of the Earth's atmosphere. For example, prior to Life, there was no oxygen molecules on Earth. Then the Great Oxidation Event made the Earth rich in oxygen nearly 2.5 billion years ago. The Rise of Oxygen "Oxygen has not always been as abundant as it is today. Most scientists believe that for half of Earth's 4.6-billion-year history, the atmosphere contained almost no oxygen." http://www.astrobio.net/exclusive/541/the-rise-of-oxygen It is expected that Life will begin to pull greenhouse gases out of the atmosphere and bury it into the sea or land, as the Sun heats up. It's already happening now. Despite the mass hysteria about carbon dioxide and global warming, the long term trend is actually that CO2 has been going down, not up. Yousuf Khan |