To celebrate the 50th Anniversary of The Bovedy Meteorite falling in Northern Ireland, some of The Education Team at Armagh Observatory and Planetarium have written pieces about their favourite meteorites and craters from across the globe.
The Mysterious Mbozi by Helen McLoughlin
The Mbozi meteorite is the eighth largest meteorite in the world and is the most popular tourist attraction found in Songwe region. It’s around 3 meters long and 1 meter tall and weighs in at an estimated 16 metric tonnes (roughly 3 times heavier than a T-Rex!)
As you can see from the picture it has quite an irregular shape with uneven notches on the pointed end, which were apparently caused by souvenir hunters hacking out chunks of it (pretty difficult task considering it’s mostly composed of strong iron!)
Its timeline is vague as no one knows the exact time that it fell but it has been known by locals for centuries. It was officially discovered in 1930 when the top was only visible. To show the whole meteorite, the hillside around it was dug away. Scientists estimate that it would have hit the earth many thousands of years ago, as there are no traces of the crater it must have made when it fell or any local legends regarding its origins. It was declared a protected monument by the government in 1967 and is now under the jurisdiction of the Department of Antiquities.
The Willamette Meteorite by Ria Mee
Discovered in 1902, the Willamette Meteorite is the largest known meteorite in the United states and the sixth largest in the World. From the beginning this meteorite caused a bit of a stir as it was initially stolen from where it was found in Oregon. It was moved the massive distance of nearly one mile by Ellis Hughes, quite an impressive task seeing as its weighs 15.5 tonnes, and although he did have the help of a wagon and horse it still took him 90 days. Ellis moved it to his own property in the hope he could claim ownership, unfortunately for him his crime was discovered and ownership was given to the Oregon Iron and Steele Company. The Willamette meteorite had been previously known to the Clackamas people (Native Americans) who named it ‘Tomanowos’.
It’s believed that the Willamette Meteorite fell approximately 13,000 years ago and evidence suggests that it was transported by glacial ice from its original impact spot, which is thought to be in Montana area or even as far as north as Canada, although no impact crater has ever been found. It is made up of 91% iron with smaller traces of nickel, cobalt and phosphorous. The Willamette Meteorite was purchased by Sarah Dodge for $26,000 at the time and gifted it to the American National History Museum in 1906, where it has been ever since.
The Chesapeake Bay Crater by Courtney Allison
The Chesapeake Bay Crater is the largest known impact site of an asteroid strike in The United States, and the sixth largest in the world. Having been to Virginia recently, I have enjoyed delving into the collective knowledge put forth by geologists, hydrologists and other scientists about this impact site that I stood so close to but I was unaware of!
Despite its notable size (52 miles across and 1.2 miles deep) the impact crater remained undiscovered until very recently. This is due to the impact site not being visible from our position on earth or even from The International Space Station – in fact it was not until 1983 that some initial clues that there may be an impact site nearby were discovered. Scientists happened upon a layer of fused glass beads called tektites by accident during a core sampling procedure; these tektites are an unmistakable sign of an asteroid impact.
The meteorite itself that slammed into the mouth of the Bay in Virginia some 35 million years ago was around 8 miles in diameter. Impacting what is now Washington DC, the aftermath of the impact in the seconds following was devastating to the surrounding region. The meteorite, which exploded upon impact, sent millions of tons of water and shattered rock into the atmosphere above the East Coast of America. Minutes after, a megatsunami flooded the surrounding land; evidence found by scientists suggest this tsunami reached the Blue Ridge Mountains, some 477 miles from the impact site! Following this, the sedimentary walls of the impact crater began to fall in and slump leading to a wider crater; during this process ancient sea-water from the time became trapped between the layers of sedimentary rock beds. It is this trapping of ancient sea-water that lead to the discovery of the crater itself in 1993. Through oil exploration, deposits of ancient sea-water were found and through years of tests scientists were able to pin point the age of the crater.
By analysing the levels of helium in the newly discovered water in 2012, they discovered the level for this gas in this sample was around 100 times higher than normal coastal water. By determining the rate at which the helium accumulated in the sea-water, scientists could figure out the age of the water. Studying ancient sea-water has real world impacts for us today on earth; by understanding how acidic the ocean was historically we may be able to gain an insight into how to tackle modern ocean acidification due to global warming. It is amazing that a meteorite from 35 million years ago is aiding us in saving our planet!
The Allende Meteorite by Heather Alexander
When it comes to meteorites, it is really hard for me to choose an absolute favourite, however the Allende always springs to mind. The reason for this is simple; it was one of two meteorites that fell in 1969, before the Moon landing even happened. The Allende meteorite fell first, in February 1969 over Mexico, and the second meteorite to fall that year? None other than the Bovedy Meteorite here in Northern Ireland on 25th April 1969. Bovedy fell in Northern Ireland and so that means we talk about it more, however Allende is a phenomenal meteorite, and here is why.
The Allende Meteorite is the largest carbonaceous chondrite ever found on Earth. These types of meteorites only make up four percent of the meteorites that have fallen from Space. It fell over the Mexican state of Chihuahua, travelling south to north, and after an extensive search over 2 tonnes of meteorite was recovered. Like a lot of meteorites, it exploded in the atmosphere and the fireball was witness by many people just after 1:00am on 8th February 1969. Due to the amount of material recovered, it has led the Allende to become “the best studied meteorite” on Earth. We have a small slice of the Allende in our collection at Armagh Planetarium!
A special feature of the Allende Meteorite, and carbonaceous chondrites, are small, white looking inclusions known as chondrules. These little globules in the Allende Meteorite are a calcium-aluminium inclusion, and these were some of the first solids ever to condense in the early formation of the solar system.
alex · May 6, 2019 at 16:51
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