New Information Regarding Meteorite's Age Suggest It's Not From Mercury
Scientists have identified the age of the meteorite thought to be from Mercury and it's not looking good - the rock is estimated to be 4.5 billion years old, which, some scientists believe, is too old for it to hail from the distant planet.
Found last year in Morocco, the green rock sparked interested once a quick evaluation proved the meteorite had a chemical makeup similar to the solar system's innermost planet.
But, some scientists are pointing out, lunar highland rocks are 4.2 to 4.3 billion years old and that Mercurian rocks are believed to have crystallized at the same time after the melt 4.5 billion years ago.
"The moon began to crystallize 4.5 billion years ago," Randy Korotev, a lunar geologist from Washington University in St. Louis, said in an interview with students, "but we don't have any 4.5-billion-year-old meteorites from the moon, because all of those rocks would have been bashed to smithereens during the late heavy bombardment that pockmarked the moon with craters between 4 to 3.8 billion years ago."
This event, also known as the LHB, refers to a sudden spike in heavy cratering that affected the inner planets. And while scientists are not sure what caused it, the dominating theory points to a rapid migration of the giant planets after their orbits adjusted and gravity shoved them out into space.
The question then, according to Korotev, "is how did this rock survive for that long? There's no sign of it being brecciated, or busted up."
What's more, Korotev said, is just how incredibly rare such a find would be given that only 1 in 1,000 meteorites are from the Moon and another 1 in 1,000 come from Mars.
At this point, the Meteoritical Society has classified NWA 7325 as an "achondrite ungrouped," meaning that they believe it came from a body like a planet or something large enough to generate enough internal heat early in its hsitory to melt partially, thus resulting in a metallic core surrounded by the rock. Beyond that, however, they remain "agnostic."