Meteorites Past and Present.

Meteorites are pieces of rock and metal that have been falling to Earth throughout history. The scars of large impacts can still be seen as craters on Earth’s surface. Humans have a long and rich association with meteorites going back thousands of years.

Meteor Crater

The best preserved crater on Earth is Meteor Crater in central Arizona. Many other larger craters have been worn away by erosion over eons since the impacts that formed them.

The Bible describes rains of stones and the metal found in meteorites was the source for iron long before methods were learned to smelt iron from ores. Recently new interest has been seen in iron beads from an ancient cemetery of the Egyptians. They were originally believed to be made from meteorites then later doubt was cast on the idea. Now they have once again been determined to be made of cosmic metal. Ancient artifacts of iron have been found in several areas of the Middle East and even among the grave goods of King Tutankhamen.

Many of these items are known to be made of meteorite iron because the structure of the metal and its nickel content prove that it is not from a terrestrial iron ore. Many of the ancient artifacts including ones from North America have been cold worked. This means the meteorite metal has just been pounded into shape without the application of heat. Cold working preserves in a distorted form the crystal pattern of the metal. These remains of the Widmanstätten pattern are proof enough of meteoritic origin.

Canyon Diablo Meteorite Heat Damaged

The structure observed in iron meteorites is not just distorted by mechanical forces like pounding and bending. The structure is damaged and distorted by heat also as this Canyon Diablo shows. It was heated too high at the time Meteor Crater formed and the Widmanstätten pattern has changed.

After ancient cultures learned to smelt iron from its various ores meteorites which are rare became far less important as an occasional and fortuitous source for iron, Thus begins the long period of superstition about meteorites. The bright meteors along with comets become omens that foretell either good or bad. Meteorites become known as thunderstones and the explanation of their origin will wait until much later. One of the early ideas about rocks that fall to the ground is that they are from volcanoes. A good guess because volcanoes do throw countless rock into the air. However, they all land relatively close to the volcano. Meteorites fall anywhere randomly. Another early idea was used for tektites also, that meteorites formed by some means as the result of lightning in the air and then fall to Earth.

It can certainly be debated as to which meteorite event brought the awakening that meteorites come from space. I personally think that after the fall of the Ensisheim stone in 1492 there was a clear connection between the atmospheric event of light, smoke, and explosions and the finding of rocks on the ground. In the case of Ensisheim there was but a single stone found. It was taken as an omen of good fortune by King Maximilian of Austria who was fighting the French near where the meteorite fell. He visited the meteorite and also won his battle. The meteorite after a lot of abuse by persons seeking pieces was moved into the town hall of Ensisheim, Alsace, France where it still remains on display.

Ensisheim Meteorite

This is a small piece of the Ensisheim meteorite and it is still looking a fresh gray color even after 500 years.

Other early recognized meteorites are Siena 1794 in Italy, L’Aigle 1803 again in France, and Weston 1807 in Connecticut the oldest witnessed meteorite event in the USA.

The small piece of Weston shown here is the first recovered witnessed fall in the United States of America.

The early researchers actually had many stones from long ago to study and compare to the meteorites which were falling and being recovered. Unfortunately little of many of these early and even ancient stones remain. In some cases poor handling and record keeping as they passed from hand to hand leaves some questions about which preserved fragment is really from which meteorite. For example, Vago is a meteorite which fell in Italy in 1668 and had at least two stones reported that were of great size. The meteorites were 136 and 91 kilograms respectively. Only three tiny fragments remain today. These fragments have some conflicts as to type. While two pieces match the chondrite stone believed to be Vago the third fragment is that of a eucrite a very different type meteorite. Valdinoce is another early stone examined and described but of the five stones said to have fallen nothing remains today.

Many other stones were studied by early investigators and what they found was the basics of what we still find true today. Meteorites have nickel iron metal in them. Native or free metallic iron is very rare on Earth. Our weather and abundant oxygen turn iron into rust very quickly. So iron is nearly always found in terrestrial rock as iron bearing minerals not metal. The early investigators also found the round structures called chondrules in many of the meteorites. Chondrites remain the largest group of stone meteorites still. The pattern of crystals in the iron meteorites was recognized quite early and named for Count Alois von Beckh Widmanstätten even though a geologist named Thompson actually discovered it slightly earlier. But, many of the early stones that were investigated have stories like Vago and Valdinoce and little remains of them.

Begaa Meteorite

The round structures seen in the picture of the meteorite Begaa are chondrules. Chondrules are spheres of minerals that cooled in space from liquid drops in microgravity.

Some other early stones did fare better than those just mentioned. They like Ensisheim were protected because of their strange arrival. After detonations were heard and a brilliant flash was seen the Nogata meteorite was found in a hole. Nogata has remained in the Shinto shrine of Suga Jinja in Fukuoka Prefecture, Japan since 861 AD. Though the box it is kept in and the writing that accompany it are more recent the date recorded is May 19, 861.

History is rich with stories of falling stones. Many of the descriptions sound very much like what a meteorite should look like. Black stones is a common phrase. But nothing remains of the stones and they now must be considered doubtful. What we do know is that meteorites fall to Earth all the time. For several hundred years they have been accepted as rare and unusual stones with an origin beyond the surface of Earth. Over the last hundred years as scientific methods have improved meteorites have given up many of their secrets. At the time of this writing, there are 45,828 officially named meteorites with an additional 10,800 provision names given to specimens not yet approved as official meteorites. This is an astronomical jump in numbers since the early days of meteorite studies 500 years ago.

Meteorites carry with them a kind of baggage. Recorded in their minerals and textures and chondrules is the personal experience of that stone. How much banging around it has suffered how much melting and recrystallizing it has endured. Or as some meteorites record, a peaceful stress free journey has brought them to Earth. These few which are pristine tell the story of an early solar system and how meteorites formed. But whether it is the record of impact, shock, melting and cooling, fragmentation and reformation or a recorded pristine state each is giving scientists a glimpse at material out in space that we are currently not able to visit.

Gao Meteorite

This is a baby sized meteorite from the fall of the Gao meteorite in 1960. Whether meteorites are big or small they all get a fusion crust during their passage through the atmosphere.

What will happen to meteorite studies in the next century when the asteroids of the solar system can be sampled directly? Will meteorite hunters still exist on Earth? Will adventuresome individuals still brave the deserts and frozen wastes of Earth to find these rocky visitors? Or will scientists be more interested in working on uncontaminated materials returned by future probes and astronauts? Right now meteorites are being brought to scientists at such a high rate that months and even years are required to find out what exact type was submitted for analysis. These are unprecedented days of abundance. New Martian and Lunar meteorites and types never seen before are being discovered and investigated nearly daily. Exciting times are still ahead and now is a great time to begin learning about these wonderful and mysterious rocks that come from space.