Space Rocks

This summer I get to do my very first independent research project. I’ll be helping one of my geology professors finish classifying a meteorite with the use of an electron microprobe. This is my first time doing such a project and as such I have a lot to learn. But that’s the exciting part of doing science: the continual learning process. So, as such I figured it was time for me to learn about meteorites. Or meteors. Or meteoroids. Each name means something different. And according to my instructor, the classification has been changing lately. So, in my efforts to learn the basics about these ancient pieces of space debris, I will be posting what I’ve learned in my blog. To start, those confusing names.

It turns out the terms meteor, meteorite and meteoroide are not interchangeable. They seem to refer to the phases of change space debris goes through as it enters the earth’s atmosphere. This rock can come from the moon, comets, asteroids or even other rocky planets (most notably Alan Hills 84001 from Mars- that deserves a post of it’s own). Some of it can be left over material from the formation of the solar system, almost 4.5 billions years old. While their origins differ they pretty much go through the same process upon encountering the earth’s atmosphere.

The difference between the three names used to be simple. The flash of light produced by the entering debris was a meteor. Any chunks of rock that broke off were the meteoroids. And any piece that didn’t disintegrate in the earth’s atmosphere and made it’s way to the surface was a meteorite.

However, a paper recently published in Meteoritics & Planetary Science by Alan E. Rubin and Jeffrey N. Grossman proposed a complete overhaul of the definitions. They suggest that a meteoroid becomes a “10 micrometer to 1 meter sized natural object traveling through interplanetary space”. A meteorite is a natural object that is larger than 10 micrometers whose parent was any rocky celestial body. The meteorite had to travel under it’s own natural means with enough velocity to escape the gravitational pull of its parent body. It then has to hit something that is larger than itself, natural or artificial, and survive the impact. What is most interesting is that the meteorite doesn’t have to hit a foreign object. If it hits the surface of it’s parent body, it’s still considered a meteorite*.

So, those are the differences between the terms. I think in the next post about meteorites, I’ll cover the classification system. And as a side note, this is my first time writing about anything of this nature. In the very unlikely chance that someone from academia (or anyone at all) reads this, please be kind with criticism. I’ll happily accept feedback if done in a professional manner.


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