Hi Ned,
Some are wrong, some are duplicitous. AiG’s main points are 1) the models of the solar nebula do not predict a dense Mercury. 2) That a magnetic field generated by a dynamo on Mercury requires a partially molten core, and Mercury shouldn’t have one. And 3) that a molten core would require sulfur, which should not be present on Mercury.
Point 1).
As usual AiG has a flair for exaggeration:
Mercury is so dense that it’s thought to have an iron core occupying some 75% of its diameter.1 This extraordinary density has generated much turmoil and confusion in evolutionary astronomy. Evolutionists mostly agree on models of planetary formation . but their models say Mercury can’t be anywhere near as dense as it actually is.
is completely out there. Planetary scientists have no real problem with Mercury's composition and density, and spectroscopic studies are consistent with standard planetary formation models. Sprague et al. (1994) detected basalt and anorthosite, and Vilas (1988) detected Fe silicates. Both detections are consistent with a refractory, high temperature location for the origin of this world. The only thing at all surprising with Mercury is its high metal:silicate ratio. There is discussion on how this came to be (namely through a catastrophic impact, see Cameron et al. 1988), but discussion does not mean that the theory is on the brink of collapse:
Only that Mercury would otherwise disprove evolution!
Answers in Genesis has a problem with geologists using catastrophes to explain the origin of things, whether the geologists are terrestrial or planetary. They seem to feel that all modern science believes in perfect uniformitarianism.
Point 2).
With regards to Mercury's magnetic field, AiG makes it seem as though since Mercury has a magnetic field, it must be young. They make this point on the fact that Mercury is too small to remain hot enough to keep a liquid core:
But as one evolutionist says, ”Mercury is so small that the general opinion is that the planet [i.e. its core] should have frozen solid aeons ago’.5 Therefore, the core cannot be molten, and so evolutionary theories would have to conclude that Mercury cannot have a magnetic field. But it does!
Aside from the normal anti-science tactics used (one evolutionist says something that may be construed as doubt, so the whole theory must be wrong!), this neglects major sources of heat- the sun, solar magnetism, radioactivity. Radioactivity may be especially important for Mercury, mainly because a lot of radioactive elements are refractory. Additionally, it neglects chemistry, which leads to point 3).
Point 3).
AiG states
A fundamental principle of the solar nebula theory (used to explain how our solar system formed) is that there cannot be any volatile elements such as sulfur this close to the sun, and so there shouldn’t be any iron sulfide in Mercury.
This is pretty much a gross misrepresentation. The Solar Nebula was likely somewhere between strictly homogenous and strictly heterogeneous (the Earth has plenty of volatiles like water due to late stage accretion). They raise a decent point about iron sulfide, but they omit any reference to any other types of sulfides or any sort of late stage gain of sulfide material. In a less oxygen rich system, high temperature sulfides form (CaS and MgS), which could add a fair bit of sulfur to the planet (see Pasek et al. 2005). Pasek et al. (2005) also suggest that the solar nebula definitely evolved to this less oxygen rich system through diffusion of water to the snow line, hence this possibility is viable. Add to that the possible detection of sulfide at the pole of Mercury (Sprague et al. 1995), and there's no reason to say that sulfur didn't make it to Mercury. Sulfur would definitely enable a long-term dynamo, especially when coupled to the external sources of heat and magnetism. Migration of material through the Solar Nebula has been known for well over 20-30 years, so there’s no excuse for AiG not recognizing this.
Refs:
Cameron, A.G.W., Fegley, B., Jr., Benz, W., and Slattery, W.L., 1988, in Mercury, University of Arizona Press, Tucson, pp. 692-708.
Pasek, M.A., Milsom, J.A., Ciesla, F.J., Lauretta, D.S., Sharp, C.M., and Lunine, J.I. 2005, Icarus 175, 1-14.
Sprague, A.L., Hunten, D.M., and Lodders, K., 1995, Icarus 118, 211-215.
Sprague, A.L., Kozlowski, R.W.H., Witteborn, F.C., Cruikshank, D.P., and Wooden, D.H., 1994, Icarus 109, 156-167.
Vilas, F. 1988, in Mercury, University of Arizona Press, Tucson, pp 59-76.
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