Alternative Venusian Temperature Explanation

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I was debating whether to put this here or in Whatnots, but it seems to serious to be Whatnots (yet not really "grave and significant" serious, so I'm not sure). Anyway, after Ragusa kindly provided me some guidence on searching, I decided to practice. I've also been thinking about something I saw on a science channel. A little background:

Venus's surface is the hottest known solid body in the solar system, substantially hotter than what it's closeness to the Sun would cause.

In the 70s we developed radio topography technology capable of mapping the surface from orbit, through the dense cloud cover. The surface we found was pocmarked with craters.

Crater distribution and density can be used to estimate the age of a planet's surface (or portions thereof). The idea is that craters formed by impacts are statistically random and, thus, regular over a period of time. The areas that have more craters are thus older, having had more time to gain craters, while the areas that have fewer are younger. Detailed studies of the Moon and rock samples taken from it support this practice.

Venus's crater distribution is statistically identical (note: URL was originally a Powerpoint Presentation file) to a completely random distribution, meaning there are no identifiable trends or tendencies. This indicates that the entire surface is probably about the same age (Earth's surface can vary wildly, from brand new to over 3 billion years old).

Venus's crater density suggests that the average age of the planet's surface is around 500 million years.

The vast majority of Venus's craters are partially, but not entirely, filled in with cooled lava.

Now, with all those facts in hand, I wish to present an alternative theory (well, not quite in the scientific sense) to the cause of Venus's excessive temperature (and it's thick atmosphere).

What if everything above there is accurate, not just for the very surface, but for the whole crust? What if the entire surface of Venus is only 500M years old, a fraction of the planet's whole life? What if the cause of Venus's insane temperatures is not it's near-primordial atmosphere, rich in greenhouse gasses, but rather that they both have the same cause? What cause, you may ask? A massive planatary impact (or alternatively a significant enough gravitational shear event to cause similar effects) could completely liquify the entire planet. This could also explain it's retrograde (backwards) spin. Imagine, an impact on the surface of Venus, perhaps 1B years ago, so large that it essentially liquified the whole planet. The temperatures are insane, hot enough to have molten steel on the surface. Gasses trapped in the rocks leak out, covering the planet in a thick, hot blanket of heat-trapping vapors. Over time, it (very slowly) cools enough to form a semi-solid shell. Something hard enough to preserve some trace of smaller asteroid impacts, but still active enough to largely fill in most if not all of them with lava flows, which then cool and harden. Eventually, it even cools to the point we see now, so that new asteroid impacts are preserved perfectly. The interior, however, is still massively hot, and this heat radiates out of the crust and into the atmosphere.

Some of you may claim that such impacts don't really happen, that they're just science fiction horrors, but astrophysicists know that, not only can these impacts happen, they have. In fact, at some point or another, every large, rocky body in our solar system was like this: as it was forming. Moreover, Earth likely went through a similarly catestrophic singular impact shortly after it formed a crust (or perhaps before). That impact not only liquified the planet, but also threw off substantial debris, which eventually congealed in orbit to become our Moon. Imagine if a similar impact happened to Venus, only more recently and more directly, so as not to produce significant castoff.

Another interesting link: Look at the bottom conclusion, possibility #2.

Now, there are other theories as to why the crust of Venus presents itself the way it does, and I don't have anywhere near the scientific training to even attempt to discredit any of them. I'm just trying to toss out an idea that popped up in my head. It's, umm, not sure how to word this, but perhaps 'romantically catestrophic' in it's appeal? Anyway, I just wanted to bounce the idea off any interested heads in here.

 

Did this come from Japan? I hear they have an expert that's been there....

 

The reason it's so much hotter than the sun should make it is because Scarlett Johansson has a summer home there.

 

...

Ok, yeah, I should have expected this. Actually, truth be told, I half did, but I also hoped.

Oh well, if you can't beat 'em, join 'em!

 

NOG: This is an interesting concept you present. However, just as you lack enough background in astronomy and physics to determine how plausible such an event is, so do I. It's interesting to consider, and I cannot say it's implausible.

 

Most scientists agree that the retrograde rotation is caused by its previous binary orbit with earth, much in the same way as pluto and charon.

also, I believe that such an impact would have not liquified the surface but sheered the planet causing venus to have rings. we would also expect her to have moons.

 

So true. I sincerely hope this is not a backhanded way to try to debunk the greenhouse effect.

 

How would this be even remotely related to the greenhouse effect?

 

I know, it was a lot of words...

 

That entirely depends on the angle of impact. The Earth's Moon-forming impact created no rings, but one single sizable moon. Still, it was an extremely oblique impact (if the theory is true). Less oblique impacts could create more stable orbital debris and create rings, or less stable ones and create rings or moons that would quickly (a few hundred million years) fall back to the surface. Certain impacts could even leave the planet whole without any significant orbital debris. Mass of the impacting body also changes things considerably.

No, not at all. Even if CO2 has no significant effect, Venus's sulfuric acid and sulfur dioxide more than account for a massive greenhouse effect. I'm just wondering if it's cause or effect.

Another problem that I've run into is that Venus has essentially no geomagnetic field. For those that don't know, Earth's massive geomagnetic field is caused by the interaction of our mostly nickel/iron core with our mostly nickel/iron mantle. The two spin at different speeds and thus move relative to each other. That essentially acts as a massive magnetic field generator, and that field protects us from most solar radiation and particles. Venus, however, has no field. For a long time, this has led scientists to believe that it therefore has no liquid mantle, but rather is solid straight through. There are, however, alternative explanations that have been raised. It could be as simple as there being an insignificant difference in spin speeds. If the mantle and core don't move relative to one another, they don't create a magnetic field. Or, either one or both could be low in magnetic particles, like nickel and iron, or the ions that feed the fields of the gas giants. We extrapolate the formation of the inside of Venus by taking it's mass, it's volume, calculating an average density, it's rocky nature, and assuming it has a similar formation to Earth. Given that information, it should have a heavily nickel-iron core and 'mantle'. However, if that density distribution isn't similar to Earth, it could be explained other ways. Perhaps the core is mostly lead, a relatively inert metal which probably wouldn't produce much of a field even under the best conditions. Again, there's no evidence either way, but there are possibilities.

 

I think one explanation is that the catastrophe that formed Earth's moon may have substantially made the Earth's core and mantle more enriched with heavier elements like nickel and iron, while more of the lighter elements like silicon were thrown off to form the moon.

 

The moon was formed from the billions of particles which were thrown off from the impact, there is nothing in orbit of Venus. The object that collieded with the Earth was disintegrated and 'joined' with the particles, over billions of years the Earth was reformed from these particles and the moon was formed as well.

Your talking about a massive impact only 500 million years ago, there would be something there.

As explained by this post as well.

Venus has no tectonic plates, resulting in reduced heat loss it simply cannot cool down, its extrememly dense atmosphere and high content of CO2 results in a massed greenhouse effect, very little escapes its atmosphere resulting in an oven effect, all heat is trapped, the sulphurous content indicates its volitile nature, Venus is believed to only lose heat during massive volcanic resurfacing events every few hundred million years.

 

Actually, Thrasher, it looks like the impact fused both cores. The Moon apparently has the same proportion of elements as the Earth does, even though it's much smaller. The proportionality is constant even down to hydrogen isotopes.

Shoshino, no, I'm expecting the actual event took place much longer ago than that. It's just that the surface cooled to a largely solid condition only 500M years ago. 1-1.5B years is plenty of time for debris to reorganize. And also, Earth's reforming didn't take "billons" of years. According to this article it may have taken as little as a month, but no more than a century. It also states that many simulations say that only about 1/2 of the ejected mass became the Moon, with the rest becoming rings, which then re-colided with the reforming Earth. Remember, we're talking drastic and sudden events here. The cooling may take eons, but the impact and orbital decays/reformations go much faster. The orbital situation likely stabalized long before the surface actually cooled.

 

Don't think so. The moon is much less dense than the Earth. It lost it's heavy metals to the Earth.

http://www.lpl.arizona.edu/outreach/origin/

Also, apparently the early Earth was very similar to today's Venus with a dense CO2 atmosphere.

 

Thrasher, that data is substantially different from what I've seen. It seems the leading theory is that the Moon's core is similarly metalic to our own, simply much smaller in proportion to the whole body (1-3%, where ours is 33%). I also learned that Mars is a lot smaller than I thought it was.

As for Venus's atmosphere, that's part of my arguement. The very early atmosphere of a planet is primarily volatile gasses that bubbled up out of the molten rock. Venus's hydrogen was stripped away by solar winds due to it's lack of a geomagnetic field, but other than that it's current atmosphere looks an aweful lot like an early planet's volatile gas atmosphere as a result of a liquified surface. The simple chemical properties and buildup of entropy should have changed the composition of the atmosphere over 3+B years, so I doubt it's simply a case of the original atmosphere never changing.

 

That's what I have heard as well. That even adjusting for size, the moon is still a lot less dense (by several factors) that the earth.

And yeah, Mercury is pretty darn small as far as planets go (but it's not Pluto-small). Then again, Pluto is no longer a planet.

 

??? Mercury? Pluto? Where'd they come from?

 

Whoops! I meant Mars - in response to your comment that Mars was a lot smaller than you thought it was. (Although in my defense, Mercury is also a lot smaller than earth. In fact, I'm pretty sure Mercury is the smallest of the eight official planets.) I only added in Pluto to say that Mars isn't terribly small as, for example, Pluto.

 

Now that Pluto's out, Mercury is indeed the smallest planet.

Interesting discussion. Unfortunately my knowledge of astrophysics isn't advanced enough to allow me to participate.

 

That isn't stopping anyone else, Ziad....