"Groove lane morphology and development consistent with that predicted for passive rifts suggest a major role of global expansion in grooved terrain formation." -- Scott L. Murchie, geologist, et al., November 1986
"The bright terrain formed as Ganymede underwent some extreme resurfacing event, probably as a result of the moon's increase in size." -- Louise M. Prockter, physicist, 2001
"In fact, it is now widely accepted that the Jovian moon, Ganymede, has experienced significant, internally-generated, post-formation expansion. As Prockter (2001) writes: 'The bright terrain formed as Ganymede underwent some extreme resurfacing event, probably as a result of the moon's increase in size'. Collins et al. (1999) agree that the formation of the grooved terrain on Ganymede was likely the result of post-formation 'global expansion'. " -- Dennis J. McCarthy, geoscientist, November 2005
"Since planets and moons did not pop into existence at their current size, everyone agrees they must have expanded at some point in their history." -- Dennis J. McCarthy, geoscientist, November 2005
"Ganymede's grooved terrain likely formed during an epoch of global expansion...." -- Michael T. Bland and Adam P. Showman, planetary scientists, 2007
"Ganymede's surface is dominated by relatively young, extensional tectonic deformation. While it is generally accepted that this deformation formed during global expansion of the satellite, the cause of the expansion remains unclear." -- Michael T. Bland, astrogeologist, et al., 2007
"Why does plate tectonics occur only on Earth? This is one of the major questions in earth and planetary sciences research, and raises a wide range of related questions: has plate tectonics ever occurred...?" Paula Martin, astrophysicist, et al., 2008
Science Daily: Scientists Complete First Geological Global Map Of Jupiter's Satellite Ganymede.
ScienceDaily (Sep. 18, 2009) — Scientists have assembled the first global geological map of the Solar System’s largest moon – and in doing so have gathered new evidence into the formation of the large, icy satellite.
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11 comments:
"Why does plate tectonics occur only on Earth?"
Water saturated rock melts at a lower temperature than non-saturated rock.
I don't see anything in the orginal article about expansion. The various terrains may be fragments of impacts that formed Ganymede, but there's no evidence that it's getting bigger.
"there's no evidence that it's getting bigger."
LOL.
So when an impact occurs you think Ganymede magically decreases in size?
Not at all. There is no evidence of on-going expansion. It's not changing size in either direction.
If something large struck it, the two might accrete into a larger moon, but the solar system has been free of large rogue objects for some time. Look up "Late Heavy Bombardment."
So when material is accreted to Ganymede it magically disappears?
"It's not changing size in either direction."
The universe is dynamic not static.
The universe is dynamic not static.
I find myself agreeing with you on that point. However, Expansion Tectonics is not happening the way you think its happening. Hell, you folks do not have a mechanism.
At least mainstream science has an an explanation for accretion, the Theia impact, for example, that formed the moon would have added mass to the earth.
Objects accrete, then grow exceedingly slowly through dust accumulation and impact, but nowhere near the rate you folks claim. It is not possible in your current hypothesis, and until it is shown to be possible, you'll get no acquiesence from me or anyone else.
Note that this post of mine begins a new phase in my rebuttals of your nonsense. No longer am I arguing points with you. I am going to point out where you are wrong and move on. As nothing will dissuade you from your position, I feel compelled to quit trying. I am now Mainstream Science's big neon sign that flashes "STUPID" at you at one in the morning. Its a dirty job, but someone has to do it.
So when material is accreted to Ganymede it magically disappears?
There you go again. Using the word magic. There is no such thing. Are you so busy you cannot say things properly?
If something accretes to an object (and I'm not sure that is the proper way of saying that either) I should think most of the material remains on site, thus the increase in size. A large portion of it is likely blown off into space if it is imparted enough velocity to escape the gravity of the impactor/impactee. Some material likely rains back down onto the surface of the new body.
@ Jeffery Keown:
Keown: "...the Theia impact, for example, that formed the moon would have added mass to the earth."
Just goes to show you are a herd animal.
The "Theia impact" is speculative at best.
There is little science to support the hypothesis (oxygen content of the Moon and Earth), but because consensus has wrapped around it -- well, you have too.
But anyway, Ganymede provides an image of tectonic plates where there are expansion areas around every tectonic plate on the entire surface.
This leads to the reasonable conclusion that the moon, Ganymede, has expanded.
Keown: "Expansion Tectonics is not happening the way you think its happening. Hell, you folks do not have a mechanism."
How do you know?
And yes, a mechanism has been put forward, that of plasma accretion.
You don't agree with plasma accretion, fine. But it's intellectually dishonest to state there hasn't been a proposed mechanism for expansion on this website.
Keown, your characterization, "It is not possible in your current hypothesis...", is false.
It's not clear how much and at what rate plasma has flowed from the Sun to the Earth.
There is evidence that in geologic ages past, and not necessarily long past, the amount and rate of plasma flow was much higher than today.
And this doesn't cover matter at the sub neutron, proton, electron level, like neutrinos and such (I'll admit I'm uncomfortable with this sub-world, as most of it is highly theoretical except for neutrinos, which there seems to be a body of scientific evidence to support it's existence).
@Anaconda
You don't agree with plasma accretion, fine. But it's intellectually dishonest to state there hasn't been a proposed mechanism for expansion on this website.
Alrighty then, allow me to backpedal wildly for a moment.
Okay, you have a mechanism. Call me when it is observed and quantified and shown to match your proposed rate of expansion (65% increase in mass over 200my).
OIM/Anaconda
That's pretty interesting modeling - hmmmmm - pity the Earth as 70% of its surface covered by water.
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