Category Archives: Daily Asteroid

CRADLES OF LIFE

Vital to planetary studies, meteorite craters also inform our view of life on Earth

One of the most fascinating aspects of planetary science is the number of geographical features shared by Earth and its sibling planets in our galaxy and beyond. Like our own, other planets have oceans, mountains, valleys, and even craters, which we associate with meteorites. Experts in geography define craters as “bowl-like depressions,” caused by violent collisions between celestial bodies or from volcanic eruptions.

Meteorite impact craters are important to researchers studying how planets and galaxies are formed. For example, they can tell scientists the approximate weight of the impactor and about how fast it was coming in. Craters can also reveal a lot about how old a planetary body is; the Moon, for example, has many “astroblemes”—meaning “star wounds”—across the central part of its farside, which is an indicator that region is older than the Moon’s smoother areas with fewer craters.

Craters also naturally excavate into the body’s crust and can provide scientists with primitive core samples and clues about the planet’s structure. Massive meteorites that hit the surface of Europa (one of Jupiter’s moons), for example, left large craters that punched through enough of the moon’s crust that researchers were able to estimate the depth of its ice shell. Further, data about the diameter and depth of the craters on Europa also clued scientists into the possibility of an ocean or warm ice layer below the ice shell.

As much as craters can tell us about a planet’s past, they are also useful as sites to further our ambitions for the future. The floor of Barringer Crater, also called “Meteor Crater” or the “Canyon Diablo Crater,” served as a training ground for NASA astronauts preparing for the Apollo missions; there, the future moonwalkers learned how to hunt for “faux moon rocks.” These return samples have been indispensable to analysts identifying lunar meteorites and

some researchers even believe a rock sample from the Apollo 14 mission may contain the first evidence of Earth material—a meteorite originating from Earth—on the Moon.

Impressive as craters may be, they too fall victim to weathering by Earth’s climate. The Wabar Craters, for example, lie in a now inaccessible desert region of Saudi Arabia and remain a mystery to the meteorite community for many reasons. First, the crater site is located in a now extremely dangerous area; political events, temperatures that can top 140 degrees Fahrenheit in the summer, and the terrain all contribute to the scarcity of Wabar material. Second, shifting sands have all but obliterated the craters, as the sand has slowly filled them over time. Finally, the material recovered from the Wabar crater site is a blend of both weathered and well-preserved irons. How the two could have been produced by the same source and lie in the same site still puzzles scientists today.

One thing, however, is certain: craters hold the key to understanding what happens when something from an alien world collides with another. Asteroids have destroyed life while also creating new environments for microbes and bacteria. On Earth, some people have made craters their home, like the city of Nördlingen, which was built inside the Nördlinger Ries impact crater in Germany. Looking forward, missions to the Moon and Mars will investigate what secrets their craters hold, which will inform how we explore–and eventually settle–our solar system and beyond.

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BACK TO THE MOON

A static test launch in preparation for the Moon…and beyond

It’s been nearly 50 years since the last time a human being visited the Moon; on December 1972, NASA astronauts on the Apollo 17 mission conducted geological surveys and sampling of the Moon’s surface features and materials. The crew also performed experiments both in-flight and during EVAs (Extravehicular Activity). Despite the mission’s success, the remaining Apollo missions were cancelled due to budgetary constraints and NASA’s shift of focus to other missions and spacecraft. The Moon has remained untouched by humans since then, but it won’t be for long. Rest assured, “We are going to the Moon,” in the confident words of NASA administrator Jim Bridenstine.

Following the Space Shuttle program, NASA’s Space Launch System (SLS) has been in development since 2011; its purpose is to provide a vehicle for NASA’s deep space exploration missions, which include flights to the Moon and Mars. Eventually, as humans develop plans for the exploration and development of space, SLS will evolve to fulfill the growing need for more powerful and capable configurations. Currently, SLS has has three variants—Block 1, Block 1B, and Block 2—that can be used in several configurations to accommodate the rocket’s payload and the thrust required for the mission.

NASA’s announcement of a static fire test, scheduled for Wednesday, September 2, is welcome news amid serious delays and setbacks that have plagued the development of the rocket platform. The test will take place at Northrop Grumman’s facilities in Utah, United States and “will help teams evaluate potential new materials, processes, and improvements for the boosters that will power deep space missions beyond Artemis III,” according to NASA. Artemis III will be the third flight of NASA’s Orion spacecraft launched on SLS and will be their first crewed lunar landing since 1972 and—perhaps even more importantly—the first mission where a woman will set foot on the Moon.

The Artemis III crew will be testing lunar water ice, a follow-up to experiments conducted during the Apollo 17 mission, where astronauts collected nearly 260 pounds of samples of lunar surface material. These “Moon rocks,” as they’re called, are not to be confused with lunar meteorites, which arrive on Earth after being catapulted into space from the Moon’s surface by some sort of collision. As many meteorite collectors know, it’s very illegal to own or sell Apollo return samples, though it’s thanks to these “Moon rocks” that we can positively identify lunar meteorites found on Earth. Not only that, but petrological analyses of the Apollo return samples and positively identified lunar meteorites can give us an idea of where on the Moon these meteorites may have originated.

The Apollo missions and upcoming Orion missions illustrate how meteorites impact academia and scientific research; studies of oriented meteorites aerodynamics even reveal how similar these rocks’ nosecones are to those we see on aircraft and rockets, like SLS. With the rapid advances the scientific community is making in technology, we can expect to learn a lot more about meteorites, asteroids, and our place in our universe.

Image Credit: NASA/MSFC

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HAMMER STONE METEORITES

Outer space meets civilization

A recent meteorite fall, dubbed the “Rainbow meteorite” by some, made headlines in April of 2019 when a fireball was spotted in Costa Rica. The meteorite, later named Aguas Zarcas, was a trifecta of rare meteorite characteristics; not only was it a witnessed fall, but a few, precious stones were “hammer stones” that crashed through a house; it was classified as a rare CM2 that rocked the scientific community with new data that could better inform their concept of how planets form and how carbon-based life arrived on Earth; and finally, the hammer stones—some which even had paint on them from the roof panel they hit—and impact artifacts were collected and preserved.

To clarify, meteorite “falls” are rare events where a meteor’s fall to Earth from outer space was witnessed by one or more credible observers. Rarer still are those instances where the meteorite actually strikes a man-made object; the meteorite community refers to these specimens as “hammer stones” and the objects they struck as “impact artifacts” or “hammer artifacts.”

Recent publications compare the “inky” Aguas Zarcas stones to “legendary carbonaceous chondrite” Murchison, a widely studied meteorite found in 1969 in Australia. Academics believe Aguas Zarcas holds similar promise to Murchison and are excited by the freshness of the pieces, which allows researchers to hunt for amino acids, proteins, and other molecules that hold clues to understanding the cosmos and our place in it. Philipp Heck, curator of the Chicago Field Museum meteorite collection, is quoted as saying “If I had to start a new museum collection for meteorites, and I could only select two, I would choose Murchison and Aguas Zarcas…If I could choose only one, I would choose Aguas Zarcas.”

Meteorites have fascinated humans since ancient times; they wove tales of these mysterious space rocks into their folklore, culture, and traditions. One of the most famous examples of this are civilizations whose worship incorporated rocks that fell from the heavens, like the “Black Stone of the Kaaba,” also called the “Kaaba Stone,” venerated by early Muslims in pre-Islamic times. This stone, believed for centuries to be a meteorite, has become deeply entrenched in Islamic tradition.

We also find meteorite-like objects described in stories from the ancient Egyptians, Greeks, and Romans, whose imagination was captivated by the thought of contact from the heavens in the form of strange rocks. In modern times, the phenomenon of a fireball is widely reported on by the international press. The most well-remembered and documented witnessed meteorite fall, for example, is Chelyabinsk: a large stone which fell in Russia in 2013. The world was shocked by dash-cam footage of a massive fireball streaking across the morning sky, bursting intermittently in bright, white flashes as it fell.

Only some of the Chelyabinsk stones were hammer stones, and they, along with the objects they hit, were acquired by museums and collectors at a premium. These special items represent brief flashes in time where objects from outer space collided with our everyday objects: mailboxes, windows, and sometimes, even cars and roof panels. The famed Peekskill 1980 Chevrolet Malibu impact artifact was sold into a private collection and has been displayed at museums around the world, and the original title and a broken tail light bulb sold for thousands of dollars at auction. Hammer stone meteorites themselves, like especially note-worthy pieces like Aguas Zarcas, are worth several times their weight in gold.

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ABOUT ME

Meteorite specialist, science writer, columnist, Emmy Award-winning host of TV’s STEM Journals and Meteorite Men, film producer, adventurer, and world traveler. I sit on the Board of Governors of the National Space Society; the Board of Directors of the Astrosociology Research Institute; the Board of Directors of the Science, Arts and Space Institute; and the Advisory Board of Deep Space Industries. If you look far enough up into the night sky, I am also Asteroid 132904 ”Notkin”.

PREPARING FOR A METEORITE-HUNTING EXPEDITION

Film director Ed Podiam said: “There is no practical way to prepare for an epiphany or a catastrophe. You tell yourself you’re ready, but then it happens regardless, for better or worse, and in ignorance of your best efforts.” I feel this insight applies particularly well to meteorite-hunting because, no matter how carefully you prepare for an expedition, you can never fully and completely “expect the unexpected,” even though the great science fiction writer, Douglas Adams, offered that as a key piece of advice to galactic travelers in his masterpiece, The Hitchhiker’s Guide to the Galaxy. The experienced adventurer plans as well as he or she can but — on the day — must always be ready to adapt, evolve, reboot, or revise the plan.

After Season One of my first television series, Meteorite Men, became an unexpected hit, there ensued a lengthy behind-the-scenes discussion about how the show runner might go about scripting Season Two. There were no scripts in Season One, just a half page, or so, of notes outlining what the director hoped to accomplish in each episode. A sample concept for a proposed Season Two script read something like: “Geoff climbs to the top of the hill in the desert and digs up a meteorite. Then he calls Steve, excitedly, on the walkie-talkie.” It was never going to work because nobody — including me — knew if there was a meteorite at the top of that hill. We had to go up there and look for ourselves, in real time, with a metal detector or meteorite-savvy eyes. Fortunately, our senior producers soon realized that you cannot script a meteorite find. Our show already had a unique and authentic pacing and the producers were understanding enough to appreciate that the only way to make a real television adventure show is to let the adventure happen the way it wants to happen … and film everything that goes down.

Here is why:

Most meteorites come to our little planet by way of the Asteroid Belt, via deep and cold space. Everywhere out there is on the way to nowhere. The average journey distance for a meteorite en route to Earth is about 250,000,000 miles. And I thought it was a long way back to London.

Every meteorite that reaches the surface of our home planet has overcome seemingly impossible, unmeasurable, and wholly cosmic odds to get here. When asteroids smash into each other — out there between Jupiter and Mars — blasting pieces in all directions, those shard-like fragments could, very literally, go anywhere: straight into another asteroid, off to frigid inter-solar-system blackness to be lost forever, or annihilated by the blinding heat and crushing gravity of our own sun. Those few fragments that do, by chance, find their way to Earth encounter moist atmosphere as fast as — well — an actual rocket, and our protective blanket of oxygen and nitrogen might cause them to skip, bounce, and hurtle back out into space. If they don’t shear away but, instead, continue plowing towards Mother Earth through ever-thickening air, they may well burn up completely, or explode into minuscule pieces as a result of a devastating and near-instantaneous temperature change. Or, most likely of all, they could just drop into the oceans that cover most of our planet, and sink. Some land in sand dunes or Arctic snowfields, are swallowed by jungles, or — as in the case of one fireball we frantically investigated — have the very poor directional sense to make landfall in the middle of a top secret military testing ground, never to be seen by human eyes.

 Geoff Notkin and Steve Arnold in Chile's Atacama Desert

In my life, a meteorite hunting expedition often begins with a phone call. That call is usually — but not always — from Steve Arnold — a hunter and adventurer of great talent and drive, and my indefatigable co-host on Meteorite Men. The gist of a recent call was: “Hey, Geoff! I’m headed to the Sahara to hunt meteorites. Wanna go?” As simple as that. Much later, I realized that the Sahara expedition dates would be — pretty much to the week — the twenty-first anniversary of our very first joint adventure to Chile’s Atacama Desert in the spring of 1997. I planned for that long-ago journey in much the same way that I planned this one. Though, I like to think I’ve learned a few things in the intervening decades.

Meteorites fall where they are going to fall. They pay no heed to the Equator, or Earth’s magnetic pole, or the government, or anything other than the unflinching rules of physics and gravity. Space / rock / atmosphere / boom. The odds are heavily against any meteorite making it all the way to Earth. The odds are also heavily against you, or me, or anyone finding it. The successful meteorite hunter, therefore, does everything possible to improve those casino-like odds.

If you intend to hunt in a place where meteorites have been found in the past, start by doing your research. Do thorough research. There was never a meteorite hunter who did too much research. On the other hand, most of us have glanced all-too-briefly at the existing conventional map of a new fall site and — eager to get out and get on with the hunt — thought to ourselves: “That area doesn’t look so big, I’ll figure it out when I get there.” And then, when you do get there, you realize “that area” stretches, foreboding and featureless, in every direction until sunset, or — worse — it is a mushy, swamp-sodden paradise for rattlesnakes and cottonmouths (this precise thing has happened to me). Perhaps, upon arrival, you realize the likely fall site is awash with densely-packed trees or corn stalks that wouldn’t consider allowing you to swing a detector among them, or maybe your favored ground is decorated with “NO TRESPASSING” signs (in New Mexico, while hunting the Glorieta Mountain strewnfield, I once saw such a sign that included the text: “SURVIVORS WILL BE PROSECUTED.”) Whenever possible, know where you are going before you get there, and pack accordingly. If you’re going to the Arctic (as I have, repeatedly), you may need snow gear. If you’re going deep into the poison-ivy rich swamps of Alabama in the summer (as I have, fortunately only once), waders and snake gaiters will be far more useful.

 The Meteorite Men off-road it to Whitecourt Crater in the Canadian winter

If a meteorite was found at the site you headed to, try and determine precisely where and under what circumstances the discovery was made. Begin your search there and work outwards. Meteorites often fall in clusters, so there may be others nearby. Was the initial find deeply buried and discovered with the help of a detector, or was it lying on the surface? The age of the fall and the type of meteorite will dictate your search methods.

Be aware that different countries have varying regulations about meteorite ownership and export, so do your homework before you head overseas. You cannot, for example, remove meteorites from Canada or Australia without explicit government permission and paperwork.

Take everything you need, but try to make sure you need everything you take. This is tricky for me, because I like to have every conceivable bit of gear I might want, but I also like to travel light. Those two concepts don’t mix well together, so I have to play Give and Take as I prepare for each expedition. Many of the things I pack in (energy bars, soluble vitamins, trail mix, etc.), won’t pack out with me because they are consumed during the expedition, hopefully making room in your bags for finds and souvenirs. Wondering what to do with those sneakers and socks that are nearly worn out? They make great expedition fodder. Wear them around camp, or on travel days, and toss them at the end of your final day in the field. If you’re operating in an underprivileged country, you may find a grateful person who will enthusiastically give a good home to the used boots, cooking pan, or old sleeping bag that you don’t want to take home. That way, if you fall in love with a camel blanket or a fez, you’ll have room in your bag to bring them back as gifts for your significant other. Or your cat (my cat has blankets from Lapland, Australia, and my favorite market in Marrakech).

The only thing better than traveling light is discovering, when you really need it, that you did bring the spare battery pack. Learning what to take, and how much of it, are acquired skills. These are some of the indispensables the serious hunter will almost always need:

GOOD HIKING BOOTS

You only get two feet and they are going to carry you everywhere you need to go en route to making your first, or next, meteorite find. My friend Mike Miller, an innovative and determined meteorite hunter, once stated the obvious when we were out in the field: “You have to walk over a meteorite before you can find it.” But sometimes obvious advice is the best advice.

Take care of your feet so they can walk over that meteorite for you. Put them inside good, sturdy, lightweight, comfy hiking boots. The comfy part is very important. If your feet aren’t happy, they won’t do a good job of porting you around the strewnfield for eight or sixteen hours a day (depending on your level of gusto). For the serious hunter, sneakers will not cut it during the long haul, especially in rough terrain. Socks are important too. On long or arduous hunts and hikes I wear thin liner socks underneath larger cotton socks. The liners wick away moisture, help prevent blisters, and also provide extra cushioning.

DAY PACK OR UTILITY BELT

Choose a lightweight day pack when doing actual hunting and always take it with you. Even on a short hike. If you make a find, or get lost, or both, a “short walk” can very quickly turn into the long hike you were not prepared for. Only put essentials in your pack. Leave your flip flops and your bedtime reading in the tent or vehicle. Some of us have been hefting packs in and out of craters and up and down mountain ranges for years or decades. Some people’s backs may have started complaining about the abuse. Osprey makes a terrific utility belt that comes with a one-liter water bottle in each of two side pockets, along with plenty of zippered pockets for other necessities. Tired back? Let your hips take the brunt for a change.

METAL DETECTOR / MAGNET CANE

If you are looking for buried meteorites you will need a good metal detector. Different detectors are better at finding different types of meteorites. Do you homework or ask me. Aerolite Meteorites, Inc. is an authorized Minelab metal detector dealer with decades of meteorite-hunting expertise and we will be glad to advise you.

We take magnet canes into the field for a reason. Almost all meteorites contain iron and will stick to a magnet. There are, however, a whole lot of rocks out there that look like meteorites, but aren’t. Using a magnet cane prevents you from bending over to pick up rocks one thousand times a day. If that doesn’t sound like such a big deal, try picking up a thousand rocks in one day, while discovering that none of them are meteorites.

GPS

When searching in known strewnfields, I log every find. That helps me understand the fall pattern of meteorites and may give me clues about the locations of other, undiscovered pieces. GPS data can be very useful to meteorite researchers who are building strewnfield maps, and a GPS can also save your life. Eager to start a desert hunt, I once took off in such a hurry that I lost my bearings. It is very easy, especially in tundra or flat desert, to forget where you parked the truck. Before you head out into the field, GPS your vehicle or campsite, so you can find your way home when you are tired and it’s getting dark.

WATER AND NOURISHMENT

Most of us know that you’re supposed to drink two liters of water a day and that’s just under normal conditions. If you’re hiking around, swinging a detector, carrying a pack, and digging in the dirt, your body needs more than that. Carry extra water. Use a Camelback or multiple canteens. I never leave the truck with less than 1.5 liters on my person.

The excitement and exertion of meteorite hunting burns a lot of calories. Take energy bars or trail mix in your pack with you. When you get hungry, miles from base camp, you’ll be glad you have them. For breakfast and dinner try to eat real food. You need energy in the field, so find a way to mix in fresh fruit, greens, and protein when you can. Crackers and sandwiches are not effective fuel for successful adventurers. I pack two energy bars, one powdered vitamin pack, and one electrolyte pack for each day I expect to spend in the field. Pour the vitamins and electrolytes into your water bottle. They taste good and ensure you get the minerals and vitamins you need.

FIRST AID AND SAFETY

I always keep a quality, folding camping knife on my belt and I carry a small first aid kit with me if I’m hunting alone or far from base. And we keep more robust first aid kits in the field vehicles. My friends who have skin cancer wish they had used more sunscreen when they were younger. Wearing a decent, wide-brimmed hat helps prevent that, and sunstroke, and also makes you look a bit like Indiana Jones, which is never a bad thing. If weather conditions might change during your field days, put a small poncho or emergency blanket in your pack. Camping gear can be very hi-tech and you can easily find examples of each that only weigh a few ounces.

In some instances, such as traveling in the Atacama Desert or the Australian Outback, we’ve taken medics and / or survival guides with us, because we were so far from civilization that an emergency evac — even by helicopter or flying doctor — wasn’t an option. It was money well spent. Hazards vary by country and season and it’s extremely valuable to have a local expert point out what’s dangerous and what isn’t.

INSECTS

Some insects are an annoyance; others are dangerous. I don’t ever wear open-toed shoes in the field, and I rarely wear shorts because both increase your exposure to bites and stings. Keep a small bottle of insect repellent in your pack and you should have antiseptic wipes in your first aid kits. I also carry a folded mosquito / fly net that’s not much bigger than a wine cork. It fits into a tiny pocket on my belt pack.

INSURANCE AND EVACS

If you are going way out there into the hostile world, as I sometimes do, you may consider investing in premium insurance services. Companies like Global Rescue offer medical and military evacs, should you find yourself in a really dicey situation. In remote areas, you are not going to have conventional cell service, so I recommend renting a sat phone for serious expeditions. They are expensive to rent and to use ($2 per minute is typical, plus rental fee for the unit), but that $2 call could save your life, or the life of a team member.

PACKING

If you are flying to your destination, be aware that most airlines charge for each checked bag and the typical weight limit is about 50 lbs per bag. Put heavy and valuable items like cameras and laptops in your carry-on, as most airlines don’t weigh them, and you don’t want that stuff thrown around by baggage handlers anyway. I invested in a small, portable hand scale that tells me exactly how much my bags weigh. It’s handy to know that before you get to the airport. On a major expedition I travel with matching heavy-duty rolling bags. I split up the big stuff: my folded-down Minelab SDC 2300 metal detector loves to travel and it goes happily in one; my hiking boots and magnet cane in the other.

We all need clothes, so wrap your detector in a field jacket or jeans for added protection. If you are driving to the hunt site, your detectors still need to be treated with care and respect. Expert meteorite hunter, Twink Monrad, is also a seamstress and she made snappy cloth detector bags for herself and her hunting partner, the late Jim Kriegh.

We use powerful rare earth magnets in meteorite hunting and they’ll be glad to wipe your credit card, hotel card key, or iPod, so I bundle one in a wool sock and put it in my hiking boot. When driving, magnets are very happy to live clamped to the bed of your truck until you need them.

FUN AND MEMORIES

Meteorite hunting is not all about the finds. It’s also about the journeys we embark upon and the friends we go with, or make along the way. Take a small camera or smart phone with you. Later, you’ll look back on adventure photos with delight. Don’t forget to pause for a moment and take an in situ photo of your find. Your friends will be impressed by when you get home and they will say: “You found that!?” You might take a little notebook and keep a daily trip journal. I always carry a thick paperback book with me too, as you never know when you might have to occupy and hour, or a day, while a tire is being changed or an airplane is being refueled.

Above all, remember that no matter how much you plan, nothing ever turns out quite the way you expected. Be nimble, like the snake who glides between boulders. Be ready to adapt to changing situations and try to appreciate the opportunities you have been given. Meteorite hunting is not for everyone, but every hunt is an adventure.

The greatest meteorite hunters know that every good find happens because of research, skill, knowledge, determination, and chance. We learned in Meteorite Men that the best adventures are always the unscripted ones and, in his memoir, Travels With Charley, John Steinbeck observed: “We find after years of struggle that we do not take a trip; a trip takes us.”

May you be taken by a good one.

To learn more, read my book, Meteorite Hunting: How to Find Treasure from Space, now available as an ebook.

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ABOUT ME

Meteorite specialist, science writer, columnist, Emmy Award-winning host of TV’s STEM Journals and Meteorite Men, film producer, adventurer, and world traveler. I sit on the Board of Governors of the National Space Society; the Board of Directors of the Astrosociology Research Institute; the Board of Directors of the Science, Arts and Space Institute; and the Advisory Board of Deep Space Industries. If you look far enough up into the night sky, I am also Asteroid 132904 ”Notkin”.

WHAT ARE METEORITES?

Ever since we humans evolved eyes through which to see, a mind with which to ponder, and a night sky to stare up at in wonder, we have been fascinated, mystified, and inspired by the shooting stars that hurtle, sparkling and brilliantly short-lived, through the darkness above us. And we have done our best to describe them in word, song, and images.

There are twenty references to shooting stars — known as meteors in science — in the collected works of William Shakespeare, alone. The novelist Vladimir Nabokov imagined that meteors were celestial trails formed when naughty angels disposed of cigarette butts, lest they be caught smoking by Gabriel. A typically self-assured Jim Morrison compared himself to a shooting star, and in the beloved fantasy novel Stardust — later adapted into a delightful feature film starring Claire Danes — my lifelong friend, Neil Gaiman, speculated that if a half-Faerie man followed a shooting star to its landing place, he would there discover a beautiful (and quite headstrong) young, blonde woman.

In my career I have, many times, followed the trail of a dazzling meteor or fireball, and many times found the extraterrestrial culprit responsible, dashed on the plains or deserts of our planet Earth. Alas, none were quite as luminous as the versatile actress Ms. Danes, but they were beautiful and alluring in their own right … and valuable too.

WHAT ARE SHOOTING STARS AND WHAT REALLY HAPPENS WHEN YOU FIND ONE?

Even though the words are similar, it is important to understand that meteors and meteorites are as different as could be. A meteor, or shooting star, is the bright streak of light we see in the night sky. It is caused when a piece of cosmic debris (usually an asteroid fragment) vaporizes as it is super-heated in Earth’s atmosphere, due primarily to rapidly increasing air pressure. The word meteor describes the atmospheric phenomenon — the actual streak of light — rather than the rapidly traveling fragment that is creating that streak of light. If any part of that fragment makes it all the way through our atmosphere without burning up completely, and lands here on Earth’s surface as a solid mass, it becomes known as a meteorite. So … all meteorites were once (briefly) meteors, but not all meteors become meteorites. Since a meteor is an atmospheric phenomenon that occurs many miles above Earth’s surface, you’d never be able to actually find one. But you can find meteorites if you know where — and how — to look, and are very lucky, skilled, or determined.

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When we do find a meteorite that is new to science, there is a rush to get a representative sample to an accredited laboratory as soon as possible. Exposure to rain and our atmosphere will soon alter, or terrestrialize, meteorites, making them less useful for scientific analysis. Later, additional samples may be donated for research, exhibited in museums, or sold to private collectors to help underwrite the high cost of expeditions and field work.

Meteorites, therefore, are pieces of solid cosmic material — iron, or stone, or a mixture of both — that fall to Earth. The are divided into three main groups and many sub-groups.

THE THREE MAIN METEORITE GROUPS

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Sikhote-Alin (iron meteorite), Brahin (stony-iron meteorite), Northwest Africa 7998 (stone meteorite)

Chondrites, the largest group of stone meteorites, are the most abundant type and account for about 80% of all known meteorite falls. They are composed of approximately 20% nickel-iron, mixed with common minerals that we also find on Earth such as feldspar, plagioclase, and olivine. Iron meteorites are quite rare and account for less than 5% of falls, while falls of the intriguing stony-irons make up only about 1%.

When a potential meteorite slams into our Earth’s moist, oxygen-rich atmosphere, its exterior temperature is raised by thousands of degrees F  — a powerful and shocking effect that will toast its surface almost instantaneously. As a result, a meteorite that is found soon after it lands will show a dark, burned, and blackened surface that is often likened to a charcoal briquette. Since nearly all meteorites contain 20 to 93% iron, it will feel heavy for its size and will usually attract strongly to a powerful magnet.

Meteorites often display fascinating surface features and unusual internal structures, all of which can be markedly different from what we are used to seeing in Earth rocks. They have great research value to scientists (a meteorite scientist is known as a meteoriticist, not to be confused with a meteorologist who studies the weather) and can also have significant financial value to private collectors and museums.

I have travelled over half a million miles across and around our planet Earth in search of meteorites. I have found thousands of them, ranging in size from smaller than a grain of rice, to a monster weighing 273 pounds (124 kg) that was buried nearly 6 feet (2 meters) underground. Hunting for meteorites, and recovering and studying them, and sharing what I have learned with millions of people through my Discovery Networks television series, Meteorite Men, my writing, photography, and lectures, have been the great adventure of my life. In this blog — Searching The Skies — I will share that adventure with you. I invite you to come along with me on an amazing journey and learn everything I know about meteorites — rare, mysterious, and fascinating visitors from space.

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