Mercury - a left-over of the crash that created the Moon?, Highly speculative but maybe worth it |
Mercury - a left-over of the crash that created the Moon?, Highly speculative but maybe worth it |
Dec 7 2007, 12:19 PM
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Member Group: Members Posts: 147 Joined: 14-April 06 From: Berlin Member No.: 744 |
Having agreed upon the Moon being created by a grazing collision with a Mars-sized object, could we give any thoughts to what happened to the impactor afterwards? Since it was a grazing collision, it might have been melted but not destroyed, only with some material ripped from it (and from the Earth) which ended up in Earth orbit to coalsce into what we know as the Moon today. But what happened to the impactor after it passed the Earth? Could it still hang around somewhere in the Solar System? I suppose it would bear some significant markings after the event, for instance have its outer layers stripped. But wait a second... Mercury DOES have its outer layers stripped off, with an unusually high mean density resulting from a core which could be considered oversized for such a small planetary body. In the wake of MESSENGER beginning to reveal Mercury's secrets in January, could anyone bother to give any thoughts to this idea? I am not sure whether it had been put forth previously or not, I am just curious if it could make any sense to have the impactor impact the Earth in a grazing manner and then end up parked in an elliptical orbit close to the Sun, with its outer layers stripped and an "oversized" original core left inside...
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Dec 8 2007, 11:39 AM
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Senior Member Group: Members Posts: 1870 Joined: 20-February 05 Member No.: 174 |
A mega impact cause for Mercury's high density has been seriously proposed, backed up by numerical simulations similar to those for a lunar origin by mega impact. In this case, a head-on impact, maybe at higher speeds, onto an object with lower mass and lower escape velocity blows a large fracton of the crust and mantle to escape velocity. Some in recaptured over time, but more is gravitationally scattered to impact Venus or be lobbed into higher eccentricity orbits by Venus, etc. It eventually ends up in the sun or scattered throughout the solar system and beyond. It's plausible, Messenger's crust composition mapping and geophysical studies will show if it's more or less plausible. Be very hard to prove.
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