By: Phil and Roslyn Heywood
“Scientists believe the first chunk of planet Mercury has landed on Earth.” (Australian Associated Press) Mercury is exceptional in having a live planetary magnetic field – perhaps only one hundredth the ‘strength’ of Earth’s, but, unlike Venus, Mars, and asteroids, it has a field. Remnant magnetism lingers in the rock of some bodies such as the moon and Mars. Venus does not have any measured magnetism as a planet and pieces of Venus have not been positively identified as meteorites.
NWA 7325 by the ‘scientist’s’ own admission, is exceptionally depleted in iron. A piece of rock coming from an exceptionally iron –poor region may (or may not) happen to be magnetically distinct, as a product of its environment. Subsequent events, such as impact shock and space travel, might also influence magnetic property.
So, an amateur such as myself is perplexed by the claim of identification of the source on the basis of a weak magnetic imprint.
Meanwhile, the chemistry, (which Prof. Irving — ex. Australian, incidentally—has published), does not entirely match what is known of the surface of Mercury. The Professor correctly suggests the meteorite may have been excavated from deep underground. It can still be Mercury.
What he does not mention is that Mercury shows every sign of having lost approximately half its rock. This may have happened by impact and/or sloughing. This would account both for Mercury’s exceptionally large iron core and its unique surface chemistry. Parts of the stripped rock (‘mantle’) may have been collected by Venus, Earth, and, (by implication) our moon. Another Australian, Professor Stuart Ross Taylor, writes as much in his standard reference on the solar system, the ‘bible’ on this topic.
What are these people talking about? What is AAP talking about?
Anyone with an interest in the significance of this green meteorite might GOOGLE under, “Significance NWA 7325 lunar origin waterway woodlands Texas”. Parts of Mercury could well be in the moon and here on Earth! There are meteorites landing here with the exact same isotope ratios as Earth and Moon – and with obvious similarities to the surface of Mercury. But even if we landed on Mercury and returned with a sample and measured the isotopes, we have not proved much. An impactor, slamming into a planet, might vaporize both itself and part of the planet – and leave a hybrid isotope reading!
Someone got bogged in a Texas swamp in the woods, and moonshine may be implicated?