Question about Venus

trumptor · Dec 28, 2008

I have a couple of questions about Venus. First of all, Venus' surface is only about 500 million years old and I read on Wikipedia that it was due to the planet not having plate tectonics to dissipate the heat from the mantle. The mantle would then cyclically heat up to a critical temperature that would create subduction to occur on a global scale which would last 100 million years. Is this the standard theory then as to why the planet's surface is only 500 my old? I believe that I read other causes for this only a few years ago.It states that the planet has no plate tectonics probably because the surface and mantle are dry. If the planet had oceans on it, then would it also have had plate tectonics? I guess what I'm most interested in is the possibility of Venus having been hospitable to life in the past and the prospects of Earth being the next in line to turn into a present day Venus.  With the Sun getting hotter over time, could Venus have been at some point in the past better suited for developing life than Earth? Life got a foothold on Earth very soon after it was possible, so couldn't the same have happened on Venus? And if conditions were better suited for life in the distant past on Venus than on Earth, could there have been plants and animals there during the billions of years of snail paced evolution here? If the entire crust has been recycled 500my ago, is there any way that we could find out if there was ever life on Venus or not?Also, with the Sun increasing heat I read an article here that it will only take another 1 or 2 billions years I believe for the Earth's oceans to boil away. Would this then create the same type of extreme subduction to occur to the Earth, removing any evidence of anything having ever been here? And also will this lead to Mars being in the middle of the habitable zone then for a billion or two years? If Mars did receive the amount of heat that Earth does now, would it have enough water to produce oceans, and would there be a chance of it resembling a small Earth of today?What I'm thinking is that the habitable zone is a ring that over time is moving outward and that obviously at the present time Earth is in the middle of it but at one time Venus was and later Mars may be, and during the Sun's red giant phase, maybe Jupiter may be, giving its moons the ability to harbor advanced lifeforms. And also, Venus may have been a planet full of life at some time in the past and we may never know. <div class="Discussion_UserSignature"> ______________Caution, I may not know what I'm talking about. </div>

trumptor · Dec 28, 2008

I think I may have went all over the place with my post. Sorry<img src="http://sitelife.space.com/ver1.0/content/scripts/tinymce/plugins/emotions/images/smiley-undecided.gif" border="0" alt="Undecided" title="Undecided" /> <div class="Discussion_UserSignature"> ______________Caution, I may not know what I'm talking about. </div>

BoJangles · Dec 28, 2008

What you’re looking for is the habitable Zone. Though, I'm not sure if the suns luminosity was that much less in the past, compared to now, as earth has always had liquid water.---Planets are in equilibrium with their surroundings: they are neither getting hotter nor colder. All planets absorb incident radiation from the Sun (this heats them up); to maintain equilibrium, they must radiate away the same amount of energy. The temperature of a planet can be approximated by assuming that it is a black body. You determine the temperature by equating the planetary luminosity (proportional to its temperature raised to the fourth power, T4) to the solar irradiance (L/D2, where L is the solar luminosity and D is the distance to the Sun). The distance at which a planet is at temperature T is proportional to 1/T2. Merely plug in the values of the upper and lower temperature to get the radii of the inner and outer radii of the habitable zone. The Above information was borrowed from here. http://www.astro.sunysb.edu/fwalter/AST101/habzone.htmlMore on the Habitable Zone can be found herehttp://en.wikipedia.org/wiki/Habitable_zoneI’d be interested to know how long Venus was in the habitable zone, if at all. <img src="http://sitelife.space.com/ver1.0/Content/images/store/10/0/4aba14ee-b7e8-4ffa-80a7-a70b930b0af0.Medium.png" alt="" />  <div class="Discussion_UserSignature"> -------------- Let me start out with the standard disclaimer ... I am an idiot, I know almost nothing, I haven’t taken calculus, I don’t work for NASA, and I am one-quarter Bulgarian sheep dog. With that out of the way, I have several stupid questions... *** A few months blogging can save a few hours in research *** </div>

3488 · Dec 28, 2008

Hi all,Yes the Sun was considerably dimmer in it's youth, approx 70% as powerful as now. The Habitable Zone back then extended roughly mid way between the current orbits of Mercury & Venus, with Earth just outside the outer edge.However, what was not considered was:1). The Earth's atmosphere back then had large amounts of CO2, far in excess of today's values, creating a large greenhouse effect being fed from massive volcanoes.2). The Earth's crust was very thin & in places almost certainly large lava lakes like Tupan Patera on the Jupiter moon Io, though there is some evidence from Australia that liquid water was already pooling in the cooler areas.This also kept Earth warm despite orbiting a much less powerful Sun.As the Earth's crust thickened & volcanism waned, the Sun was increasing in luminosity, thus maintaining a staus quo. Volcanism on Venus is a different topic altogether. Certainly the evidence gained from the SAR imagery from the Magellan Venus Orbiter certainly paints a picture that most, if not all of the Cytherean surface is of the same age, approx 500 MYO, based on the impact crater distribution.Theory is & that is all it is at the moment, is that Venus unlike Earth is a single plate planet. Heat accumulates below the crust & in places hot spots punch right through flooding the entire surface with a new layer of lava.A few things need explaining are like the Maxwell Montes (including Venus's tallest mountain Maxwell Mons @ 11,500 metres / 37,300'. Difficult to see how that could be flooded unless it is crustal folding. However also evident are many individual volcanoes, so smaller eruptions must be occuring & that the dense atmosphere is being maintained despite lack of a global magnetosphere & being only approx 0.67 AU from the Sun (Venus's atmosphere is being lost to the solar wind, but at a rate far slower than Mars due to the much greater gravity of Venus). 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>

dragon04 · Dec 30, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'>I think I may have went all over the place with my post. Sorry Posted by trumptor</DIV>One thing we don't (at least Ican;t think that we do) know is WHY Venus' surface is so "new". Maybe a honkin' big impactor smacked into Venus 500 million years ago. Maybe one big enough to slow its rotation to almost a stop. From scientific models I've seen of the impactor that resulted in the formation of our own Moon, I certainly cant see how it would have been impossible that it happened to Venus.I don't think Venus is close enough to the Sun to be anything close to tidally locked.   <div class="Discussion_UserSignature"> "2012.. Year of the Dragon!! Get on the Dragon Wagon!". </div>

jim48 · Dec 30, 2008

Yes. Absolutely. You didn't even need my help with this one! <img src="http://sitelife.space.com/ver1.0/Content/images/store/6/2/b6c959d4-3ab4-46cc-828f-afd34106b7be.Medium.jpg" alt="" /> <div class="Discussion_UserSignature"> </div>

Boris_Badenov · Jan 1, 2009

Replying to: <DIV CLASS='Discussion_PostQuote'>One thing we don't (at least Ican;t think that we do) know is WHY Venus' surface is so "new". Maybe a honkin' big impactor smacked into Venus 500 million years ago. Maybe one big enough to slow its rotation to almost a stop. From scientific models I've seen of the impactor that resulted in the formation of our own Moon, I certainly cant see how it would have been impossible that it happened to Venus.I don't think Venus is close enough to the Sun to be anything close to tidally locked.   Posted by dragon04</DIV>Venus also has a retrograde orbit. That is another link in the giant impactor theory. It got hit so hard it both slowed down & flipped over. <div class="Discussion_UserSignature"> <div align="center">. </div><div align="center">Never roll in the mud with a pig. You'll both get dirty & the pig likes it.</div> </div>

MeteorWayne · Jan 1, 2009

Replying to: <DIV CLASS='Discussion_PostQuote'>Venus also has a retrograde orbit. That is another link in the giant impactor theory. It got hit so hard it both slowed down & flipped over. Posted by boris1961</DIV> Must be early morning flibbity gibbities. You meant rotation.It's orbit is prograde, just like all the other planets, and 99% of the other flotsam of the solar system. <img src="http://sitelife.space.com/ver1.0/content/scripts/tinymce/plugins/emotions/images/smiley-laughing.gif" border="0" alt="Laughing" title="Laughing" />And BTW, the impactor is not required to explain Venus' rotation. I read a paper last year showing that it is one of several possible outcomes of it's interaction with other solar system bodies. <div class="Discussion_UserSignature"> But the Krell forgot one thing John. Monsters. Monsters from the Id. I really, really, really, really miss the "first unread post" function </div>

trumptor · Jan 1, 2009

If there was ever life on Venus, would there be a way we could find out? Would they leave any traces in the atmosphere? Considering that life is extremely robust with all the new extremophiles found over the years would it be possible that if there was any life that there may be some type of microbial life still in the upper atmosphere?  I'm assuming that if Venus was resurfaced by a gigantic meteor then it'd probably be impossible for life to have hung on, but if it were something more gradual could there still be something there? <div class="Discussion_UserSignature"> ______________Caution, I may not know what I'm talking about. </div>

neilsox · Jan 2, 2009

We have numerous clues what happened on Earth a few million years ago, but they become few and unreliable farther back in time. Carbon dating and most other radioactive dating also become iffy. We make assumptions such as no change in the laws of physics, and no one terraforming or fine tuning the changes. Venus and Mars have the same problems, but worse, as we done detailed examination of only tiny parts. I have never seen an explanation of why we think the surface of Venus is only 500 million years old, nor why we think the Sun was 70% cooler about 4 billion years ago, other than some math equations also based on assumptions that may be wrong. Otherwise your further projections seem reasonable. Venus might have been 400 degrees c cooler 4 billion years ago and Mars may be 30 degrees c warmer in one billion years. Some increase in Mars' air pressure is likely as Mars gets warmer. We think Earth took a billion years for photo synthesis to produce a 20% oxygen atmosphere. Why would we expect Mars to make oxygen faster? My guess is Earth will warm less than 30 degrees c in one billion years. That hot will be inconvenient, requiring humans and other critters to move closer to the poles. If we move an average of 3 millimeters per year toward the poles that is 3000 kilometers in one billion years. 30 degrees warmer at the equator will not boil the oceans. That is assuming the sun really is getting hotter.   Neil

Boris_Badenov · Jan 2, 2009

Replying to: <DIV CLASS='Discussion_PostQuote'>Must be early morning flibbity gibbities. You meant rotation.It's orbit is prograde, just like all the other planets, and 99% of the other flotsam of the solar system. And BTW, the impactor is not required to explain Venus' rotation. I read a paper last year showing that it is one of several possible outcomes of it's interaction with other solar system bodies. Posted by MeteorWayne</DIV>[sound of palm smacking forehead] <img src="http://sitelife.space.com/ver1.0/content/scripts/tinymce/plugins/emotions/images/smiley-surprised.gif" border="0" alt="Surprised" title="Surprised" /> <div class="Discussion_UserSignature"> <div align="center">. </div><div align="center">Never roll in the mud with a pig. You'll both get dirty & the pig likes it.</div> </div>

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