Our Space

The meteorite is shown next to a gouge it made in the wood floor of the upstairs bedroom. The rock measures about 4 by 6 inches and weighs just a little over 2 pounds.The fireball was a small event with a total estimated energy of one ton of TNT. A typical meteorite this size hits the ground moving around 200-250 miles an hour.

A recent unusual news headline described a space rock crashing through the roof of a house in New Jersey. No one was hurt, but the misnomers in the press were quite prolific, so let’s fix the confusion: what’s the difference between a meteor, a meteoroid and a meteorite?

Fun fact: they are actually three different stages of the exact same thing – a space rock. If that space rock, which can range in size from a tiny dust grain to an asteroid, is doing its thing out there in space, traveling around the sun or any other celestial body, it’s called a meteoroid. Once that space rock is on a collision course with Earth and starts to enter its atmosphere it will create a light show: its speed coupled with the ever-increasing thickness of the air results in so much friction that the rock begins to glow. Now that space rock becomes visible to the human observer. We sometimes call them shooting stars, but the phenomenon is properly called a meteor. And if something of that space rock survives and actually ends up on the surface of the planet (or the Moon or any other celestial body, in fact), it is called a meteorite.

You can help yourself remember that by thinking of how the names of many minerals found on Earth end in -ite.

Meteorites come in many different “flavors”, but there are three main types: stony meteorites, iron meteorites, and stony-iron meteorites. The first kind is the most common – about 85% of all meteorites found on Earth are stony meteorites. Iron meteorites contain a high percentage of metallic iron-nickel, and the last kind is a mix of the two, as the name implies. Most of them are leftovers from the formation of the solar system, so yes, they are ancient.

But not all meteorites were free-ranging loners. We have meteorites that originally came from the Moon or from Mars. The Moon and Mars get hit by space rocks all the time, and some of them are so big that the impact is violent enough to blast surface rocks into space. This is how the infamous Mars meteorite ALH 84001 that made headline news a few decades ago for possibly having fossilized bacteria in it ended up on Earth. The Mars Rovers have found several examples of meteorites on the Red Planet. Since Mars has such a thin atmosphere the likelihood of a large space rock surviving all the way to the surface is much higher there. Likewise, the Moon’s craters are a reminder that the next big impact might happen anytime!

Meteor Crater in Arizona is one of the most well-preserved impact craters on Earth, but evidence of past impacts can be found everywhere, often disguised by vegetation or erosion, and not every meteorite makes a crater. The vast majority of them are so small they simply burn up in the atmosphere or explode into tiny pieces long before they reach the ground. 

Meteorites can theoretically be found all over the planet, but since most of them look like ordinary rocks only in-depth analysis can tell them apart. But there are places where they stick out like a sore thumb, like in the Arctic and Antarctic, or in desert sand dunes. Meteorites are generally very dark in color, covered in soot from their journey through the atmosphere, so they are easy to spot against the white of the ice or the light colored sand of a desert. Every year, expeditions trek across the frozen or arid wastelands looking for meteorites for scientific study. And sometimes the space rocks end up in a bedroom in a house in New Jersey.

There might be microscopic meteorites in your back yard or on top of your car or even in your hair right now, since there is a steady rain of space dust falling down on Earth, and most of it is the leftovers from larger grains of dust. The larger fireballs often send meteorite hunters out into the areas where pieces might be found, but it’s very tough to find one around here.

Several times a year the Earth crosses the dust trail of a comet, and that’s when we get a so-called meteor shower. Typically named after the constellation from which they appear to originate, they are very predictable, and some of them will produce meteors every few minutes or even seconds. But you can see them pretty much any night when the skies are clear and you’re in an area with little light. Allow your eyes to adjust to the darkness and look up. You might see the blinking lights of an airplane, the faint trail of a satellite or the bright golden glow of the International Space Station, and sooner or later you’ll spot a meteor. Their bright trails usually last only a fraction of a second, but the larger ones can go on long enough to produce a visible trail across the night sky. 

Learn more about meteorites, how to find and identify them and much more at https://ares.jsc.nasa.gov/meteorite-falls/what-are-meteorites/ 

Beate Czogalla is the Professor of Theater Design in the Department of Theatre and Dance at Georgia College & State University. She has had a lifelong interest in space exploration and has been a Solar System Ambassador for the Jet Propulsion Laboratory/ NASA for many years. She can be reached at  our_space2@yahoo.com   

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