Quote:
Originally Posted by Celestial Mechanic
This is where your argument went wrong. Nothing after this statement matters.
Albedo is a measure of the ability of a surface to reflect light. It depends on the composition of the surface (cloudy atmosphere? liquid ocean? ice? dirt? soot?) and the condition of the surface (smooth? rough?). The Earth would exhibit the same albedo whether its core was made of osmium or creamy nougat.
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Wrong assumption about the justification for my assumptions.
I threw out the small icy moons with high albedos because they are most likely very icy - I didn't throw out Europa - as I said, this was a curve fitting exercise based upon the assumptions 1) Newtonian mechanics don't work. 2) If the solar system is a system of captured planets rather than an accretion ring, the average density of all of the planets should be about the same. I was shocked when the curve fit so well, I was even more shocked when I realized how many of the Mars probes appear to have fallen very fast.
I can't stress enough how important the gravity anomaly data is: If you get very close to a moon or planet, the acceleration due to local gravity is is more perturbed by variations in the local gravity field. If you over-or-under estimate the mass of the planet as a whole, you will miscalculate the mass distribution, based upon orbital gravitational harmonics. That's what is happening - Messenger's quick look at Mercury is just the short version.
I have stated that I think that the mass of Mars is ~14% greater than Newtonian estimates. The moment of inertia determined for Mars is 0.366 compared to that of the Earth: 0.3308 That's 111%; which basically assumes a lighter core and heavier crust. That is not unreasonable if you assume Mars cooled faster than the Earth, but it does not explain how or why the surface of Mars under rifts and such should be ultra light, as flyby data indicate. Venus has a moment of Inertia that is slightly less than the earth's, 0.2%; so when you look at the over-dense chasma, you have to ask why the moment of inertia is not higher, too.