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Author Topic:   Mercury's Magnetic Field
jar
Member (Idle past 394 days)
Posts: 34026
From: Texas!!
Joined: 04-20-2004


Message 31 of 42 (248872)
10-04-2005 2:19 PM
Reply to: Message 30 by Matt P
10-04-2005 2:14 PM


Re: Density, composition, and rotation
Okay.
So when we look at the planets we've discussed so far, Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, do we find anything related to their magnetic fields that appears to be an anomaly?

Aslan is not a Tame Lion

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Matt P
Member (Idle past 4775 days)
Posts: 106
From: Tampa FL
Joined: 03-18-2005


Message 32 of 42 (248874)
10-04-2005 2:25 PM
Reply to: Message 31 by jar
10-04-2005 2:19 PM


Re: Density, composition, and rotation
No, not really, as far as I know. I think that given what we now know about composition, mass, radius, and rotation rate, most everything seems to fall in place. That's probably an oversimplification, but it's not unreasonable.

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NosyNed
Member
Posts: 8996
From: Canada
Joined: 04-04-2003


Message 33 of 42 (248938)
10-04-2005 7:09 PM
Reply to: Message 32 by Matt P
10-04-2005 2:25 PM


falling into place
No, not really, as far as I know. I think that given what we now know about composition, mass, radius, and rotation rate, most everything seems to fall in place. That's probably an oversimplification, but it's not unreasonable.
So is there a problem with Mercuries field or not? This whole thread is about it being anomolous in some way is it not?

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Matt P
Member (Idle past 4775 days)
Posts: 106
From: Tampa FL
Joined: 03-18-2005


Message 34 of 42 (248951)
10-04-2005 7:29 PM
Reply to: Message 33 by NosyNed
10-04-2005 7:09 PM


Re: falling into place
As far as I know, no. Mercury is very dense, with a sizable iron core and likely a hot center, perfect for a magnetic field.
The details aren't clear, especially with regards to its slow rotation rate, but that's part of the reason for the upcoming Messenger mission. The Mariner mission didn't really cut it as far as giving us all the details.

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NosyNed
Member
Posts: 8996
From: Canada
Joined: 04-04-2003


Message 35 of 42 (248958)
10-04-2005 7:45 PM
Reply to: Message 34 by Matt P
10-04-2005 7:29 PM


no problem?
There are references in the AIG link in Message 6. Are they wrong or have been used misleadingly then?

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Matt P
Member (Idle past 4775 days)
Posts: 106
From: Tampa FL
Joined: 03-18-2005


Message 36 of 42 (249121)
10-05-2005 1:51 PM
Reply to: Message 35 by NosyNed
10-04-2005 7:45 PM


Exclamation points in scientific papers are bad.
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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Xeriar
Inactive Member


Message 37 of 42 (249322)
10-05-2005 11:16 PM
Reply to: Message 31 by jar
10-04-2005 2:19 PM


Re: Density, composition, and rotation
So when we look at the planets we've discussed so far, Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, do we find anything related to their magnetic fields that appears to be an anomaly?
Well, Mercury isn't an anomoly, more like "Insufficient data for proper analysis" - the MESSENGER probe intends to fix that. AFAIK the leading candidate is that the outermost shell of Mercury's core is still slightly liquid, due to tidal interferance by the Sun, which is significantly stronger on Mercury than the Moon's pull is on Earth.
Similar for Uranus' field:
Uranus - Wikipedia
Note that it may just be a property of massed hydrogen to generate a magnetic field, or something similar, and not just the 'big kids' like Jupiter and Saturn. Or it may be that some known, but as-of-yet undetected phenomenon is playing around beneath the planet's clouds.

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NosyNed
Member
Posts: 8996
From: Canada
Joined: 04-04-2003


Message 38 of 42 (249340)
10-06-2005 12:55 AM
Reply to: Message 36 by Matt P
10-05-2005 1:51 PM


Thank you, we have finally arrived at the answer asked for
Thanks Matt, I think that is the answer to the opening post.
It is, as suspected, the typical stuff put out by AIG.

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roxrkool
Member (Idle past 989 days)
Posts: 1497
From: Nevada
Joined: 03-23-2003


Message 39 of 42 (249506)
10-06-2005 11:44 AM
Reply to: Message 36 by Matt P
10-05-2005 1:51 PM


Re: Exclamation points in scientific papers are bad.
Great post, Matt! Thanks.

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Replies to this message:
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Matt P
Member (Idle past 4775 days)
Posts: 106
From: Tampa FL
Joined: 03-18-2005


Message 40 of 42 (249837)
10-07-2005 1:44 PM
Reply to: Message 39 by roxrkool
10-06-2005 11:44 AM


Thank you!
AiG also seems to have problems with Saturn's rings, Io, Mars, comets, and pretty much the rest of modern science.
However, those subjects are best reserved for another topic altogether.

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cavediver
Member (Idle past 3644 days)
Posts: 4129
From: UK
Joined: 06-16-2005


Message 41 of 42 (261572)
11-20-2005 1:08 PM
Reply to: Message 21 by Matt P
10-03-2005 6:03 PM


Missed this whole thread...
Just thought I'd add that if you quote...
Oh! The densities of the gas giants-
Jupiter- 1330
Saturn- 700
Uranus- 1300
Neptune- 1760
...it is a crime not to point out the great fact that Saturn floats in water
This message has been edited by cavediver, 11-20-2005 01:09 PM

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Tony650
Member (Idle past 4033 days)
Posts: 450
From: Australia
Joined: 01-30-2004


Message 42 of 42 (261585)
11-20-2005 2:49 PM
Reply to: Message 41 by cavediver
11-20-2005 1:08 PM


Re: Missed this whole thread...
Heh, years ago when I first read that, I remember thinking how cool it would be to see. Of course, the logistics of such an experiment have been a work in progress ever since.

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