Is the Planet Venus Young?

by Tim Thompson

Copyright © 1994-2003

s Venus a "young planet"? Could it be only a few thousand years old, as opposed to the few billion that standard theories would imply? I will look at Venus in what I consider the 3 major aspects of the planet: its atmosphere, its surface, and its interior, in order to explore the question of the age of Venus.

Atmosphere

Suppose that Venus were young, and very hot. One could explain the very high temperature of the lower atmosphere of Venus as heat left over from its recent creation, passing through the crust, and heating the atmosphere. However, standard theory ascribes the high temperature in the Venusian troposphere to a "greenhouse effect" caused by abundant carbon dioxide (CO₂). If one were to choose the heat-through-the-crust option, then one must demonstrate that the greenhouse explanation is either wrong, or inadequate. How might one do this?

One hopeful argument, and the most common in the Velikovskian community, is that such a greenhouse requires more water than is found in the lower atmosphere of Venus. There has never been a quantitative demonstration of this claim, Though there are references to outdated literature. So it has only the value of an assertion, until supported by some calculational or observational evidence. However, on the side of standard theory, we find in the abstract for Schofield & Taylor (1982): "Only carbon dioxide, sulfuric acid, and water vapor are considered as significant sources of opacity, and the role of the latter component was found to be minor".

While water vapor is not evidently needed to maintain a current greenhouse effect in the Venusian atmosphere, there is reason to believe that more water than seen now would be needed earlier, when the "run-away" greenhouse was still "running away". observations of the elevated D/H [*] ratio in the Venusian atmosphere imply that the atmosphere of Venus once contained more water than it does now, but the water was lost due to increasing heat through attendent, and definable, escape mechanisms. This historical model of the Venusian atmosphere can be found described, for instance, in Houghton (1979), Kahn (1982), Prinn & Lewis (1984), and more recently in Donahue & Hodges (1992), or Hunten (1993).

[*: D = Deuterium, H = Hydrogen. Deuterium is hydrogen with a deuteron instead of a lone proton as an atomic nucleus. A deuteron is a proton bound to a neutron. In common water, a known percentage of the hydrogen atoms will in fact be Deuterium instead. Therefore, the ratio of D/H in an atmosphere should be related to the mixing ratio of water in that atmosphere. If the atmosphere is found to have an elevated D/H ratio (in other words, too much Deuterium), the most likely explanation is that hydrogen has been depeleted in proportion, due to the escape of water from the atmosphere at an earlier time.]

The clear point is that there is no reason to believe that a proper greenhouse effect cannot be maintained by the current dry atmosphere of Venus. There is clear observational evidence that the atmosphere once had more water than it does now, and the means by which this water has since escaped can be demonstrated quantitatively. There is no need to invoke any non-greenhouse origin for the elevated tropospheric temperature on Venus.

Another argument seen is that the Pioneer Venus (PV) mission measured the infrared (IR) flux from Venus, and found a large excess emission, implying that the system was imbalanced strongly, and that Venus was found to be much warmer than equilibrium with insolation would presume. Any objective view of these observations, extensively reviewed in Hunten et al. (1983), does not show any such an imbalance. However, here on talk.origins, Ted Holden has expressed his own opinion on the matter, in no uncertain words, on numerous occasions. For instance:

From: medved@access1.digex.net (Ted Holden)
Subject: Venus: Another piece of the big picture
Date: 6 Aug 1994 22:52:47 -0400

[ ... ]

I claim that empirical evidence involving Venus is being doctored and falsified at every turn because it does not fit with scientists' pre-conceived ideas involving the age of our solar system, and because it does not match any of the logical requirements of Carl Sagan's "super-greenhouse" theory.

[ ... ]

Which is astonishing on the face of it, even aside from the clear statement by Taylor that the Pioneer Venus data is significantly more accurate than any prior measurement, and the clear implication that any and all past readings should simply be tossed.

Mr Holden's opinion is entirely based on these two critical points. The first point, that the data are being faked in order to avoid any possible agreement with Mr. Holden's own pre-conceived notions, is nothing more than a bald assertion. To ignore facts simply by claiming that the opposition are deliberate liars is really the last refuge of a scoundrel anyway, and I have no intention of addressing the matter, other than to assert with equal conviction that this claim is blatantly false.

The second, and far sneakier point, almost seems to make sense, and could easily trap the unwary. I will only mention in passing that if Taylor [F.W. Taylor, in chap. 20, Hunten, et al. (1983)] really had meant to imply that all data prior to PV should be "tossed out", then he could easily have said so more directly, or in fact, since he was the lead author of the paper in question, he could have simply done it. But he didn't do it, nor did he say it, nor did he imply it. We don't need Mr. Holden to tell us what Taylor "really" meant.

Despite claims to the contrary, scientific data does not come with an expiration date attached. I've never seen a laboratory notebook that included a phrase like "these data not vaild after 5/5/2000". For instance, in Hunten, et al. (1983), on page 30, in a chapter by V.I. Moroz, there is a table of measured albedos that spans 1893-1968. Mr. Holden roundly rejects the 19th century data as something that should be tossed out on the grounds that it is too old. This is wrong. In 1893 they knew how to measure magnitudes, and they did a good job. While current methods might produce higher precision, they are not likely to be much more accurate. Since the data do not suffer from any identifiable internal flaws, their cavalier dismissal is not acceptable, and would be questioned in any scientific venue. Mr. Holden claims that including these brightness measures in the list of albedoes for Venus is improper. I claim that it is not.

However, the albedo is calculated from a more fundamental quantity, namely the radiated energy flux. The entry probes from PV, which dropped into the Venus atmosphere in 4 locations, reported excess IR flux, over what was expected, once they had penetrated beneath the clouds. This was pointed out in Hunten et al., (1983), by Taylor, and others. However, as shown by Revercomb et al. (1982), Revercomb et al. (1985), and Sromovsky et al. (1985), these measurements were adversly affected by design and engineering flaws, some of which could be identified and corrected. The corrected fluxes did not show the previously reported excess. Mr. Holden calls this "doctoring the data", but any objective assessment can see what is really being done. Fixing a mistake is not "doctoring data".

A rigorous look at these PV data find them to be too affected by noise, uncertainties in calibration, or systematic flaws, to make any conclusion from them about net radiative balance. Indeed, it is not even all that clear what really constitutes radiative balance. In Hunten et al., (1983), Tomasko, in ch. 18, page 606, says that "If Venus is in equilibrium with absorbed sunlight, it should emit 150 +/- 45 W/m^2 corresponding to an effective temperature of 227 +15 -20 K.". 45 W/m^2 is an uncertainty of 30%, which leaves a lot of room for the experimental errors to fit a radiative balance, or a radiative imbalance. But, there is another way to examine the question of radiative balance.

The other way is to perform radiative transfer calculations on the Venus model atmosphere(s), and determine, from our knowledge of the atmosphere's constituents and structure, what its radiative characteristics should be. There were other instruments on the PV mission, besides radiometers, and they were used to characterize the atmosphere of Venus with far more detail than could have been achieved remotely. There have, in fact, been several studies along this line. For instance, Schofield & Taylor (1982), Kamp et al. (1988), and Kamp et al. (1990) have all demonstrated that the known physical structure of the atmopshere is consistent with its known surface temperature, in radiative balance with the sun, or at least nearly so. There is no indication here of severe imbalance, nor of excess internal heat expressed at the surface.

One can also examine the question by an inverse process. If the atmosphere of Venus really is being heated through the surface, it should be convective. The Earth's atmosphere is heated in just this way, by a surface heated via absorption of sunlight, and the Earth's troposphere is dominated by convective transport. However, the atmosphere of Venus is well known to have a sub-adiabatic temperature profile in the troposphere, which means stability against convection. this is not consistent with an atmosphere heated from below, as by a hot surface, but it is consistent with an atmosphere that absorbs most of the incoming radiation higher up, and this is consistent in turn with the fact that only about 2% if solar radiation reaches the surface of Venus.

So we see that not only is there no positive evidence in favor of the claim that the atmosphere is severely radiatively imbalanced, but there is positive evidence that it is not. Of course, should Venus be slightly out of balance, radiatively speaking, this would not be much of a surprise. After all, the gas giant planets are known to radiate considerably more energy than they receive from the sun, and even the Earth itself is very slightly imbalanced on the warm side.

Surface

The problem of energetic imbalance is not one likely to be expressed only in the atmosphere. The energy required by the Velikovskian scenario must come from within the planet. If we don't see it in the atmosphere, perhaps we should look elsewhere, for the tell-tale signs of excess heat.

This already creates a new problem, for, as Taylor himself pointed out all the way back in Hunten et al. (1983), so much heat transported through the crust should cause slumping in large topographic features. PV, and prior Earth based radar measurements, were not consistent with such an internal heat source. He also realized that to provide such heat through volcanism was inconsistent with our knowledge of volcanism on the Earth. This lead Taylor to openly reject the idea, long before Mr. Holden had come up with it (Hunten et al. (1983), P. 658).

More recent data supplied by the high-resolution radar on the Magellan probe allows us to characterize the topography, and volcanism on Venus with far better reliability than could be done a decade ago. It is so obvious that the heat energy required to force the desired imbalance cannot come through the crust by conduction, that even Mr. Holden has evidently abandoned that line of argument, in favor of ...

"That, of course (the little thing about "awesome" volcanic activity), is more or less what Magellan tells us."

Referring once again to Hunten et al. (1983), page 658, Mr. Holden tells us that power amounting to 20% of the total solar input, or about 1.5 x 10^15 Watts, needs to be emitted via the surface of Venus to account for the perceived radiative imbalance. Thanks to James Acker, of the Goddard Space Flight Center, we know that this requires a minimum of about 157,000 Kilauea size volcanoes to be active at any moment on the surface of Venus, with the added requirement that all of the magma exuded therefrom must solidify in about 24 hours(!). This is an outrageous requirement from any reasonable geophysical system. This is what Taylor realized in 1983 when he rejected the idea to which Mr. Holden still holds firm.

So, are there enough volcanoes on Venus, really, to account for the excess heat required by the Velikovskians, should they manage to get by the atmospheric arguments? According to Mr. Holden, Magellan says yes. According to Magellan, Magellan says no. For instance, Head et al. (1992) mapped the volcano distribution over 90% of the Venus surface, using Magellan data. They cataloged 1660 landforms and deposits, 550 shield fields, 274 intermediate volcanoes, 156 large volcanoes, and 86 caldera like structures. They also determined that an equilibrium re-surfacing model would imply a volcanic flux of about 0.5 cubic kilometers per year, which is comparable to the same activity on the Earth, about 0.3 to 0.5 cubic kilometers per year.

See also Phillips & Hansen (1994), Crumpler et al. (1993), and Head et al. (1991). Against these quantitative studies of volcanism, and the observed surface distribution of volcanoes, all Mr. Holden can drum up are vague and imprecise claims that there are "lots of volcanoes". This is unconvincing.

Another constant claim is that the Magellan images show a "fresh, young" surface on Venus, and this supports the claim of "awesome" volcanism. This claim, however, also does not stand up to examination. Here, see for instance, Schaber et al. (1992). They mapped a database of 874 craters over 89% of the surface of Venus. The craters ranged from 1.5 to 280 kilometers in diameter, and are randomly distributed over the surface. Of these, 62% are pristine, and only 4% are embayed by lava flows. If Venus were subject to current "awesome" volcanism, or if it was even in the fairly recent past, it is hard to explain why only 4% of its surface craters would be embayed. See also Strom et al. (1994), and Bullock et al. (1993).

Mr. Holden derisively complains about scientists and their "resurfacing fairy", and insists that the obvious real explanation is a Velikovskian young Venus. However, this is seen to be just another bald assertion, once again unsupported by facts, or the reasonable interpretation of facts. The studies cited here clearly explain the logic and methods behind their determination of the age of the resurfaced areas, through cratering statistics. Anyone in doubt can read and judge for themselves.

In short, the surface features of Venus are all consistent with what one would expect to see on an old Venus. The tell-tale signs of a young Venus are not there. No help for the Velikovskian so far, but the worst is yet to come.

Interior

The real tragedy of the Velikovskian scenario comes with the interior of Venus. The interior of Venus, at least in composition, is not unlike the interior of the Earth, which is basically true of Mars and Mercury as well. All of the "terrestrial" planets are made up of varying proportions of pretty much the same stuff, as extensive observations would imply. The most powerful argument that can be raised against the notion of a young Venus is that the current Venus is "Way Cool", or, in other words, much too cold.

Suppose Venus really were "young". Suppose it were molten only a few thousand years ago. What would it look like now? Probably about the same, molten. However, we know that Venus is not molten now, because our landers, and Soviet landers, have landed on a solid surface. Furthermore, we know from the extensive topographic relief long since verified by Earth- and spacecraft-based radar, that the crust of Venus is thick. It must be, anywhere from 30 to 70 km thick (Baisukov et al. (1992)), in order to support visible relief. Is it possible for Venus to cool so much, so rapidly, between then and now?

George R. Talbott thought so, and he even published a real mathematical model to back up his claim (Talbott, 1978). However, his model suffered from a serious attack of the blahs, as all he did was use a simple Stefan-Boltzmann cooling algorithm, the same one you would apply to a toy ball, and applied it to Venus. He even verified in the laboratory that it was applicable to the toys. In order to apply this toy equation to Venus, he invoked "forced convection" to rapidly move magma from the interior to the surface, but then turned around and calculated the cooling as if there were no thermal gradient at all between the surface and the center. However, convection is caused by thermal gradients, so these conditions are mutually exclusive and serve to destroy the credibility of Talbott's model.

Well, needless to say, this exercise of Talbott's, while perhaps curious or interesting, was certainly not applicable to Venus, or any other planet, nor for that matter to anything at all that is the size of a planet.

The business of analyzing planetary interiors is another of those tasks, like radiative transfer in an atmosphere, in which great strides have been made in relatively short time. New techniques, and rapidly increasing computational ability have allowed the field to plow forward. There have been numerous studies of the Venusian interior. See, for instance, Arkani-Hamed (1994), Phillips & Hansen (1994), Arkani-Hamed et al. (1993), Janle et al. (1992), Basiukov et al. (1992), Head (1990), and Marchenkov et al., (1990).

The known physics of planetary interiors provides perhaps the strongest argument of all against the idea of a young Venus. There is simply no way to dump the excess heat so fast. The papers cited here, and references therein, show how long the thermal time constants are for such material, and expressly show how slow cooling really becomes once a crust is formed. George Talbott's "forced convection" is a fantasy, in view of the real viscosity of planetary material under the physical conditions found inside Venus, or inside the Earth. There can be no question but that Venus would be very much hotter than it is today, if it were thousands of degrees hot only a few thousand years ago.

Conclusion

I have covered what I thought were the big 3 topics here, but there is one additional item that comes up from time to time, and that is the question of the anamolous spin of Venus. While the planet does exhibit a peculiar retrograde spin, this is also not something that can be explained only by a recent catastrophic past encounter between Earth and Venus. The details can be found, for instance, in McCue & Dormand (1993) and Shen & Zhang (1988). The spin of Venus can be re-created by gravitation over a long time span, or produced by catastrophic means that involve known suspects (inner solar system asteroids), as opposed to planetary encounters.

The conclusion, so far, is obvious. There are few, if any, observational reasons for believing that Venus is a geologically, or historically young planet. There are copious reasons, on the other hand, for believing that it is not, and cannot be young.

References

[This list contains all papers referenced in the body of the message. It may also contain papers not referenced above if I think they are useful enough to include]

Arkani-Hamed, Jafar, "On the Thermal Evolution of Venus", JOURNAL OF GEOPHYSICAL RESEARCH - PLANETS 99(E1): 2019-2033 (1994).

Arkani-Hamed, Jafar; G.G. Schaber & R.G. Strom "Constraints on the Thermal Evolution of Venus Inferred from Magellan Data" JOURNAL OF GEOPHYSICAL RESEARCH - PLANETS 98(E3): 5309-5315 (1993)

Baisukov, V.L. et al., editors "Venus Geology, Geochemistry, and Geophysics" University of Arizona Press, 1992

Bullock, M.A.; D.H. Grinspoon & J.W. Head "Venus Resurfacing Rates - Constraints Provided by 3-D Monte-Carlo Simulations" GEOPHYSICS RESEARCH LETTERS 29(19) 2147-2150 (1993)

Crumpler, L.S.; J.W. Head & J.C. Aubele "Relation of Major Volcanic Center Concentration on Venus to Global Tectonic Patterns" SCIENCE 261(5121): 591-595 (1993)

Donahue, T.M. & R.R. Hodges "Past and Present Water Budget of Venus" JOURNAL OF GEOPHYSICAL RESEARCH - PLANETS 97(E4): 6083-6091 (1992)

Duncan, Martin J. & Thomas Quinn "Long-Term Dynamical Evolution of the Solar System" ANNUAL REVIEW OF ASTRONOMY AND ASTROPHYSICS 31(): 265-295 (1993) [Not referenced above, but a very handy, and current review of our knowledge and understanding of the evolution of planetary orbits in the solar system - very useful demonstration that there is nothing about the orbit of venus that is not perfectly in keeping with standard interpretations]

Head, J.W.; L.S. Crumpler; J.C. Aubele; J.E. Guest & R.S. Saunders "Venus Volcanism - Classification of Volcanic Features and Structures, Associations, and Global Distribution from Magellan Data" JOURNAL OF GEOPHYSICAL RESEARCH - PLANETS 97(E8): 13153-13197 (1992)

Head, J.W.; D.B. Campbell; C. Elachi; J.E. Guest & D.P. MacKenzie "Venus Volcanism - Initial Analysis from Magellan Data" SCIENCE 252(5003): 276-288 (1991)

Head, J.W. "Processes of Crustal Formation and Evolution on Venus - an Analysis of Topography, Hypsometry, and Crustal Thickness Variations" EARTH, MOON AND PLANETS 50-1(Jul-): 25-55 (1990)

Houghton, J.T. "The Physics of Atmospheres" Cambrodge University Press, 1979; 13 chapters, 203 pages, ISBN 0-521-29656-0 [paperback] ... ISBN 0-521-21443-2 [hardback]

Hunten, D.M. "Atmospheric Evolution of the Terrestrial Planets" SCIENCE 259(5097): 915-920 (1993)

Hunten, D.M. et al. "Venus" University of Arizona Press, 1983; 30 chapters, 1143 pages, ISBN 0-8165-0788-0

Janle, P.; A.T. Basilevsky; M.A. Kreslavsky & E.N. Slyuta "Heat Loss and Tectonic Style of Venus" EARTH, MOON AND PLANETS 58(1): 1-29 (1992)

JOURNAL OF GEOPHYSICAL RESEARCH - PLANETS 97(E8) -- 25 AUG 1992 Special Issue: Magellan at Venus 97(E10) - 25 OCT 1992 Special Issue: Magellan at Venus, Part 2 [Several of the papers cited herein are from these two special issues. However, there are many more uncited papers that are of value to anyone interested in the Venus question.]

Kahn, R. "Deducing the Age of the Dense Venus Atmosphere" ICARUS 49(1): 71-85 (1982)

Kamp, L.W.; F.W. Taylor & S.B. Calcutt "Structure of Venus Atmosphere from Modeling of Night-Side Infrared-Spectra" NATURE 336(6197): 360-362 (1988)

Kamp, L.W. & F.W. Taylor "Radiative-Transfer Models of the Night Side of Venus" ICARUS 86(2): 510-529 (1990)

Luhmann, Janet G., et al., [editors] "Venus and Mars: Atmospheres, Ionospheres, and Solar Wind Interactions" American Geophysical Union, Geophysical Monograph #66, 1992 ISBN 0-87590-032-1; ISSN 0065-8448 [17 chapters, 430 pages; notable for chapter 2: "Chemistry of Atmosphere-Surface Interactions on Venus and Mars", an extensive review of the effect of the surface on the chemical composition of the atmosphere]

McCue, J. & J.R. Dormand "Evolution of the Spin of Venus" EARTH, MOON AND PLANETS 63(3): 209-225 (1993)

Marchenkov, K.I. et al. "The Stress State of Venusian Crust and Variations of its Thickness - Implications for Tectonics and Geodynamics" EARTH, MOON AND PLANETS 50-1(Jul-): 81-98 (1990)

Phillips, R.J. & V.L. Hansen "Tectonic and Magmatic Evolution of Venus" ANNUAL REVIEWS OF EARTH AND PLANETARY SCIENCE 22(): 597 (1994)

Prinn, R.G & Lewis, J.S. "Planets and Their Atmospheres" Academic Press, 1984; 5 chapters, 470 pages, ISBN 0-12-446582-X [paperback] ... ISBN 0-12-446580-3 [hardback]

Revercomb, H.E. et al. "Net Thermal Radiation from the Atmosphere of Venus" ICARUS 61(3): 521-538 (1985)

Revercomb, H.E. et al. "Reassessment of Net-Radiation Measurements of the Atmosphere of Venus" ICARUS 52(2): 279-300 (1982)

Schaber, G.G et al. "Geology and Distribution of Impact Craters on Venus: What are They Telling us?" JOURNAL OF GEOPHYSICAL RESEARCH - PLANETS 97(E8): 13257-13301 (1992)

Schofield, J.T. & F.W. Taylor "Net Global Thermal Emission from the Venusian Atmosphere" ICARUS 52(2): 245-262 (1982)

Shen, M. & C.Z. Zhang "Dynamical Evolution of the Rotation of Venus" EARTH, MOON AND PLANETS 43(3): 275-287 (1988)

Sromovsky, L.A. et al. "Temperature Structure in the Lower Atmosphere of Venus - New Results Derived from Pioneer Venus Entry Probe Measurements" ICARUS 62(3): 458-493 (1985)

Strom, R.G.; G.G. Schaber & D.D. Dawson "The Global Resurfacing of Venus" JOURNAL OF GEOPHYSICAL RESEARCH - PLANETS 99(E5): 10899-10926 (1994)

Talbott, George R. "The Cabots, the Lowells, and the Temperature of Venus" KRONOS IV(2): 3-25 (1978) [Section III: "The Temperature History of a Large Mass Initially at 1500 to 6000 Degrees Kelvin, Cooling by Radiation into a 200 Degree Kelvin Sink, Covering 3500 Years"; pages 11-25]