John Sinclair from the Pisgah Astronomical Research Institute (PARI) gave an excellent talk on NC meteorites for our May meeting. John is the curator of the meteorite collection at PARI (Pisgah Astronomical Research Institute) in Rosman NC near Brevard. The PARI site was originally a NASA tracking station during the 1960s and 70s and later became a DOD satcom site. Today, PARI is a non-profit institute supporting radio and optical astronomy research and education.
We learned that there are 29 sites in North Carolina from which meteorites have been recovered. Many of these were found after visual sighting of a meteor streaking across the sky. Others were unearthed by farmers plowing their fields.
Chelayabinsk Meteor
The most notable of these is an iron meteorite weighing over 100 lbs found in Randolph county in 1930 that is referred to as the Uwharrie meteorite. An observed meteor fall in Pitt county in 1934 was visible across the state with the shock wave felt across 4 counties. Meteorites from this fall were quickly recovered and are called the Farmville meteorite. The largest meteorite found weighed over 100 lbs. The Farmville meteorites are examples of Stony meteorites. One of the Farmville meteorites is on display in the NC Museum of Natural Sciences (NEC 3rd floor).
John explained the different kinds of meteorites and talked some about their origins as debris from comets, the asteroid belt or the Moon and Mars. He explained how scientists have recovered a number of meteorites that are believed to be chunks of Mars, blown off by large asteroid strikes in the distant past, that have fallen to Earth. Meteorites are classified mainly as Iron, Chondrite (stony) and Stony-Iron meteorites based upon their composition. Most meteorites found are Stony types.
Farmville Meteorite
Meteorite Cross Section
John also showed us some beautiful images of thin sections (30 microns thick) cut from meteorites that are used to study the structure and composition of these objects. Shining polarized light through the thin sections produces some beautiful and artful images. To see some thin sections from meteorites believed to have originated on Mars, go to John’s MeteoriteUSA website (link at end of this article) and open the Meteorite Thin Sections tab.
So, do we need to worry about being struck by a meteor? Not really, but people and homes have been struck a few times. In February 2013, the Russian city of Chelyabinsk experienced a near miss from a Stony LL Chondrite meteor that is estimated to have been 60 feet wide, weighing 10,000 tons and travelling at 40,000 mph. Fortunately for the people of Chelyabinsk, this meteor entered Earth’s atmosphere at a shallow angle and exploded 100,000 feet up about 20 miles south of the city. The explosive force of this meteor’s disintegration was equal to that of a large nuclear warhead. A steeper entry angle centered on Chelyabinsk would have destroyed the city. This near miss damaged thousands of buildings, collapsed a factory roof and injured over 1000 people. Seismographs in the region measured ground tremors of 2.7 on the Richter scale.
The club thanks John Sinclair for his presentation and the NC Museum of Natural Sciences for letting us meet in the Daily Planet Theater.
To learn more about meteorites and PARI, use the following links.
General Links:
- http://sites.naturalsciences.org/faqs/meteorite.html
- http://www.meteorite.com/
- https://solarsystem.nasa.gov/planets/profile.cfm?Object=Meteors
More about the Farmville Meteorite: https://naturalsciencesresearch.wordpress.com/2013/02/15/meteorite-impact-chelyabinsk-russia-and-farmville-nc/
Chelyabinsk Meteor Video (amazing footage): https://www.youtube.com/watch?v=dpmXyJrs7iU
Play ImpactEarth: http://www.purdue.edu/impactearth/
John Sinclair’s MeteoriteUSA website: http://www.meteoriteusa.com/index.htm
Pisgah Astronomical Research Institute: http://www.pari.edu/
