History of Earth and the Solar System
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A Former User last edited by
From here:
Of particular interest, Manfred Schidlowski argued in 1979 that the carbon isotopic ratios of some sedimentary rocks found in Greenland were a relic of organic matter. There was much debate over the precise dating of the rocks, with Schidlowski suggesting they were about 3800 Ma old, and others suggesting a more "modest" 3600 Ma. In either case it was a very short time for abiogenesis to have taken place, and if Schidlowski was correct, arguably too short a time. The Late Heavy Bombardment and the "re-melting" of the crust that it suggests provides a timeline under which this would be possible; life either formed immediately after the Late Heavy Bombardment, or more likely survived it, having arisen earlier during the Hadean. Recent studies suggest that the rocks Schidlowski found are indeed from the older end of the possible age range at about 3850 Ma, suggesting the latter possibility is the most likely answer.<sup>17</sup>
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A Former User last edited by
The "superscript" formatting tool seems not to work.
The "nobbc" one doesn't works either! -
A Former User last edited by
The collision ... was enough to vaporize some of the Earth's outer layers and melt both bodies. A portion of the mantle material was ejected into orbit around the Earth. ... The ejecta in orbit around the Earth could have condensed into a single body within a couple of weeks. Under the influence of its own gravity, the ejected material became a more spherical body: the Moon.
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A Former User last edited by
Are you using the forum as a personal note?!
I'm educating you
Formation of the Moon:
The collision ... was enough to vaporize some of the Earth's outer layers and melt both bodies. A portion of the mantle material was ejected into orbit around the Earth. ... The ejecta in orbit around the Earth could have condensed into a single body within a couple of weeks. Under the influence of its own gravity, the ejected material became a more spherical body: the Moon.
, in another article,
This impact vaporized a large amount of the crust, and sent material into orbit around Earth, which lingered as rings for a few million years, until these rings condensed into the Moon.
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sgunhouse Moderator Volunteer last edited by
Josh is somewhat more interested in science generally than the typical forum-goer would be. Perhaps that's why they didn't like him at the DnD Sanctuary?
As far as that last post ... it's hard to imagine anything astronomical happening "within a couple of weeks". Well, when it comes to condensing anyway. If the material was ejected as a single molten blob (already "a single body") then I suppose - but it is hard to imagine that scenario. I've never seen any sort of impact produce a single large piece of ejecta; more often you see hundreds of pieces of varying sizes.
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A Former User last edited by
The collision ... was enough to vaporize some of the Earth's outer layers and melt both bodies. A portion of the mantle material was ejected into orbit around the Earth. ... The ejecta in orbit around the Earth could have condensed into a single body within a couple of weeks. Under the influence of its own gravity, the ejected material became a more spherical body: the Moon.
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blackbird71 last edited by
Formation of the Moon:
The collision ... was enough to vaporize some of the Earth's outer layers and melt both bodies. A portion of the mantle material was ejected into orbit around the Earth. ... The ejecta in orbit around the Earth could have condensed into a single body within a couple of weeks. Under the influence of its own gravity, the ejected material became a more spherical body: the Moon.
One key problem with the lunar collision theory is the appearance of over 1000 lunar transient events noted during the last 350 years since the invention of the telescope. These events include observed bright spots, red spots, streaks of light, misty-looking areas, and colored glows on the moon's surface, each event covering areas smaller than several miles and lasting for but a few hours. The collision theory for the moon's origin assumes a consolidation of displaced earth crust and dust in the cold of space, perhaps causing a temporary period of radioactive-induced compressive volcanism, but one which would have died out long ago if the moon came into being 1 to 3 billion years ago. Current terrestrial geological evidence and understanding prohibits a more recent time for such a lunar-creating collision to have occurred. In other words, the necessary time-frame of the collision theory posits that the moon must currently be geologically inactive or dead, especially near its middle and upper strata regions, with residual lunar volcanism (if any) hopelessly locked deep within the innermost core of the body because of heat radiating into outer space over a billion or more years.
Yet in 1971, Apollo 15 detected high concentrations of radon-222 near Archistarchus Crater. That gas has a half-life of less than 4 days, so it had to come as a gaseous discharge from deep within the moon - implying volcanic transport activity. NASA, in its Technical Report R-277, indicates 11 sites on the moon where transient lunar events have been concentrated, particularly near Aristarchus and Alphonsus craters. In 1992, French astronomers observed a haze-like brightening near the central peak of Langrenus crater. Lunar heat flow measurements made during the Apollo missions demonstrated instances of unexpectedly high lunar heat flow. The lunar collision theory notwithstanding, something akin to volcanic activity is still occurring on the moon.
The net effect of that evidence is that, because the current collision theory for the moon's origin cannot explain the surface or near-surface volcanism on the moon, it implies such a moon-origin theory is problematic at best and incorrect at worst.
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blackbird71 last edited by
Never heard of that.
That's a common problem with observations that don't fit the currently ruling paradigm in science - they get relegated to the shelf to be ignored or neglected. A great many "neat" scientific explanations find their "neatness" disintegrating once a curious inquirer starts digging into the odd details here and there. This is especially true where the target of the popular theory involves something that occurred in the "deep past". For example, the implications of the details of polonium halos existing in mica grains which are found in certain primordial granite is another observation that just doesn't fit into conventional terrestrial geological theories, timescales, and sequences - so the popular theories conveniently ignore the observations. This ignored-evidence phenomenon is as old as man and his theorizing. Probably it happens because at any given stage of human existence, the science and its theories don't exist in the objective vacuum that adherents continually pretend they do. They instead exist in a cultural-political matrix that deems certain points of view inadmissible because their implications excessively challenge the current general paradigm and threaten the various power centers of those espousing the accepted theories.
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A Former User last edited by
Have some docs?
Anyway, scientist can't all conspire against truth. It's too unlikely.
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sgunhouse Moderator Volunteer last edited by
Mind you, some of the volcanism could be due to tidal effects. I'm no expert to be able to say how much, but there should be some caused by the effects of the sun's gravity. (Yes, of course the moon is tidally locked to Earth hence tides caused by Earth would be moot.)
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A Former User last edited by
Tidal heating does exist.
Read on certain satellites of our gigant planets - Neptune, Saturn, Jupiter.
Those moons in question are small enough, way too far from the Sun and not at all young to retain any initial radioactive heating, let alone that derived from the initial gravitational condensing (short-lived energy, I reckon). But due to immense gravitational disruption from their parent planets, they have it all: their core (or rather mantle) is constantly mashed by tidal effects, thus producing enough heat to warm up the crust, have volcanism, whatnot. Because of that, scientists seek possible life there: Europe, Io, Titan, some others...Considering our Moon, tidal forces applied to it must be not very sufficient to heat its interior, however...
As to some elements that might be "seen evaporating" or like that, first our Moon wasn't too active to begin with to have its stuff have already got sufficiently/ultimately convected, so same elements that got there during its formation might still be there - going through time to time (due to same tidal effects, eg); second, the Moon never had any stable atmosphere and was/has been heavily bombarded by STUFF - especially that during The Late Heavy Bombardment. -
blackbird71 last edited by
The problem with our moon and possible tidal effects causing lunar volcanism is that the moon always keeps the same face oriented toward the earth as it orbits, so there is no differential pushing and pulling on varying internal lunar masses to trigger internal tidal effects (and subsequent heating) on the moon. At a surface spot on the moon, the earth always appears to remain in the same place in the sky. The moon experiences a largely constant pull of the earth, but it's always mostly the same magnitude and in the same vector direction relative to the moon's surface and internal structure. Any back-and-forth tidal actions to generate heat would have to originate entirely from the variances of solar attraction as the moon orbits both the earth and, elliptically, the sun - but these forces alone have never been deemed by science as sufficient to cause volcanic heat levels on objects as small as the moon. So the apparent volcanism remains, as does the inadequacy of the current collision theory as an explanation.
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A Former User last edited by
- Never heard of any significant volcanic activity on the Moon.
- There are tidal forces:
- the Moon's orbit is not circular;
- there is the Sun, and __Earth'__s (the Earth-Moon system's) orbit around the Sun is not circular either;
- there are other planets, and occasional meteorites - that can bring
shitstuff onto the Moon (mind p.1).