STORIES FROM THE VAULT: Space Rocks

On a February morning in 2013, a meteor traveled through the skies above Russia’s Ural Mountain region.  Scientists estimated the meteor had a force 20 times more powerful than the Hiroshima bomb, however it exploded at a much higher altitude and the atmosphere acted as a shield.  The meteor’s intense flash of light was momentarily brighter than the sun and its shockwave shattered more than a million square feet of glass, which left approximately a thousand people injured.

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Although such meteor strikes are rare, meteorites can be found anywhere on Earth.  Meteors are solid pieces of rock and metal that have broken away from larger pieces of extraterrestrial debris, such as asteroids.  They accelerate to speeds of over 11.2 kilometers per second once they enter the Earth’s gravitational force, but their speed slows down and they turn into bright glowing balls of fire due to friction from entering the Earth’s atmosphere.  If the meteor survives impact with the Earth’s surface, it is called a “meteorite.”  Meteors often impact uninhabited areas, such as open fields, forests and the ocean.  Perhaps one of the best places to find meteorites is in Antarctica – thousands have been recovered here, since they are easy to spot against the white landscape.

The Morris Museum has several meteorites that exhibit interesting clues about their origins.  One of them, known as MET-4, is part of the Allende meteorite, the largest carbonaceous chondrite found on Earth, which landed in the Mexican state of Chihuahua  in 1969.  MET-4 contains a black coating on its exterior that formed from the fiery entry of this meteorite into the Earth’s atmosphere (see photograph below).  This meteorite is classified as a carbonaceous chondrite, or stony meteorite – these are the most primitive forms of meteorites and they only account for around 4.6 percent of all meteorites found on Earth.  The ingredients in chondrites offer us interesting clues about the earliest history of our Solar System and how it formed long before there were any planets.  MET-4 contains large, calcium-aluminum rich inclusions, which are among the oldest elements in our Solar System.

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Meteorites can measure a fraction of a millimeter to the size of a football field and beyond.  The Morris Museum’s MET-6 is a fragment from the Canyon Diablo meteorite that formed Barringer Crater (also known as Meteor Crater) in northern Arizona around 50,000 years ago (see photograph below).  This crater, which has become a national tourist attraction, is 550 feet deep and around one mile wide.  MET-6 is an iron, octahedrite meteorite that is composed of metallic nickel (see photograph below).  Octahedrite meteorites come from the metallic cores of asteroids and dwarf planets.

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Most meteorites originate from the collision of two asteroids in space.  Other meteorites come from the Moon and Mars.  Recently, it was determined that a newly discovered collection of meteorites contains a very different composition from other meteorites previously known. Researchers are still pondering where in our Solar System these meteorites could have originated from.  Another meteorite, known as NWA 7325, is green in color (see photograph below by Stefan Ralew) and researchers believe it could have came from Mercury, or a body similar in composition to that of Mercury.

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Meteorites provide scientists with valuable clues about the origins of our Solar System and the makeup of other planets, without having to travel to these planets. Certain carbonaceous chondrite meteorites even contain amino acids – the building blocks of life.  More than seventy varieties of amino acids have been found in meteorites.  Some scientists believe that life’s key ingredients could have formed in space and possibly been delivered to Earth long ago by meteorites.

To see more of the Morris Museum’s meteorite collection, and to learn about things from out of this world, come to the Morris Museum’s Astro Day on Saturday, March 22nd, from 11:00 am– 4:00 pm.  Night Sky Observing Hours will be 7:00-9:00 pm, weather permitting.
By Maria Ribaudo, Collections Manager