The habitable planet bubble

Greg at Oklo.org has recently put a price on terrestrial planets, as the successful launch of the Kepler telescope has piqued various people's interest in these worlds. More recently, he has announced a prize for the first planet to exceed a million dollars on his pay scale. Just for comparison's sake, he rates the Earth at 4 quadrillion dollars on this scale, while the small, cold Mars comes in at a paltry 13 grand. No currently known exoplanet can even match this value, with Gliese 581b maxxing out at just over $500. However, there is at least one low hanging fruit.

A few weeks ago, coming home from work just after sundown, I noticed a bright terrestrial planet hanging low in the western sky. As I am a women's tennis fan, I decided to name this planet after my favorite player.

The value of Venus in the oklo.org valuation is strongly dependent on its calculated blackbody temperature, which in turn depends on albedo. Using the known value of 0.75, the blackbody temperature of Venus is -40 degrees C, which is chilly, but still close enough to habitable to return a handsome 348 trillion dollars.

Assuming an albedo of zero raises the temperature by almost 100 degrees to a toasty 55 degrees C. This impacts the valuation considerably, giving a total value of only 81 trillion dollars because the planet is too hot. But 0 and 0.75 are both extreme values for albedo. What if we use something more moderate?

The purpose of the exercise is to find terrestrial planets, so assuming a terrestrial albedo (0.36) seems to be the most reasonable place to start. This assumption gives an average Venusian temperature of 20 C. That's an almost identical to the current temperature here in Canberra, and a pleasant 68 F for American readers. Plugged into the valuation formula, this model for Venus returns a staggering 1.44 quadrillion dollars. In fact, this valuation is only 20 trillion dollars short of the 1.46 quadrillion dollar value derived for the Earth using the known terrestrial albedo number. This value also puts me clear of the million dollar jackpot threshold by about nine orders of magnitude.

Of course, pedantic observers may note that Venus's blackbody behavior is tempered by the fact that the planet has a thick atmosphere, which warms the surface via the greenhouse effect. We can calculate this second order effect by substituting T_eff (the model blackbody temperature- 230-330K depending on albedo) with T_real, the actual surface temperature of 737K. This drops the valuation from 1440 trillion dollars to 2.9x10^-89 dollars, or 2.9x10^-87 cents. But in the current financial environment, a mere 104 order of magnitude decrease is not a problem. Rather, it is a badge of honor. Who wouldn't want ten thousand googles in times like these? Were I an investment manager instead of a geologist, I could use that as a justification for a million dollar bonus paid by congressional bailout.

Compared to this planetary overvaluation, the housing bubble is imperceptible.

Here are the values for some other solar system objects:
Moon: 7x10^-25 dollars. (size matters)
Europa: 7x10^-47 dollars. (This makes the JIMO EJSM program 56 orders of magnitude over budget)
Ganymede: 1.2x10^-37 dollars. (The European half of that mission is relatively thrifty)
Titan: 9.5x10^-44 dollars. (compare this with Greg's hypothetical exomoon)