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The posts are in reverse chronological order, and are pegged by topic on the links to the left. For more of an introduction, please see the About this site page listed above.

Tuesday 2 April 2019

Meteorites!

Hello! Been a while since we spoke about space stuff, so let's take a look at the smashing topic of meteorites!

Late last year, my girlfriend and I had the pleasure of visiting the Météorites: Entre Ciel et Terre (between sky and Earth) at the Muséum National d'Histoire Naturelle in Paris. While I had learned about meteorites in school, I had never been to a museum exhibit about them before, so I was excited to learn more!




 So, what is a meteor? What is a meteorite? Well, as explained below, any piece of naturally-occurring space debris which enters the Earth's atmosphere is a meteor; only material which successfully hits the ground is a meteorite. Meteors burning up in the atmosphere cause shooting stars.



The world has had a long history with meteorites. There was the one which contributed to the end of the dinosaurs, there was the one which landed in Russia six years ago, but in between, meteors have been a strong part of our world history and culture.



Humanity's perspective on the universe is quite fascinating. While it differs culture to culture, it is interesting to consider the evolution of ideas. For some, at one time, the Earth and sky were all that there was, and all existed as one solid object. Stars were simply landmarks of the divine, and meteors? Well, they could only be fallen pieces of heaven, right? Sightings of comets, asteroids, and large meteors were quite rare, and thus were considered to be prophetic, an omen of something extraordinary.

One thing that is really fun to think about is that iron, in its metal state, is almost inexistant in nature. Thus, before the invention of metallurgy, meteoritic iron was used to make things like weapons and jewelry. Often, those decordated with divine faces and symbols were deemed more precious. Tutankhamun, King Tut, the famous Egyptian pharoah, was entombed with a dagger made from meteoritic iron.





Meteorites come in all shapes and sizes, affected by their composition and journey through the atmosphere. Those who study meteors are known as planetary scientists, or sometimes meteorists/meteoricists. Another fun fact, the reason we have/use the term meteorology to mean the study of weather is because it comes from Greek, and was used to refer to anything which fell from the sky, such as rain. Planetary scientists study meteorites in order to better understand Earth's atmospheric composition and that of the universe. 

While we have probes exploring other worlds, sleep well Opportunity, meteorites provide us a perspective on outer space, while staying here at home.



One thing I learned more about in this exhibit was the prevelance of meteorites in modern history. While we tend to think of these falling rocks as isolated events, it is estimated that 5,000 meteorites around 1 kg each, fall each year. And there have been numerous accounts of them.


Sometimes, the accounts can be quite amusing. If no one sees the rock falling, they do not usually know where it came from. So, you have stories of people finding holes in their homes or cars, or even, strangely enough, several stories of meteorites found in briefcases. Basically, people would find interesting rocks, put them in storage, and when family sorted out the belongings years later, someone would realize, "Hey, this is a meteorite!" Which you can tell based on the rock's composition and structure.



Ever wondered what a meteorite smells like! Well, as one 19th century testimonial put it, "Fresh meteorites smell like rotten eggs!" Here, we had a chance to actually try it for ourselves, and yes, I can confirm that. Makes sense, of course, given that any sulphur-like materials would vapourize in the atmosphere into hydrogen sulphide or sulphur dioxide. Of course, this smell of hellfire only helped to add to the fear that meteorites were bad omens, along with the streaks of light burning across the sky!


"Why does anyone study space? How does it help us?" are common questions I hear from people who have little perspective on planetary science or space exploration. Well, let's take a look at our own planet. 



In some places, such as the Badlands in western Canada, it is possible to look at the history of our planet's evolution. In this location, we can literally examine the different layers to better understand the composition of the Earth, the atmosphere, etc., all by looking at the chemical composition. However, there are limits. Earth is a constantly changing place. Techtonic plates shift and submerge, volcanoes spew lava all over, and meteorites have violently struck the surface of Earth in the past, destroying evidence of the past.


However, meteorites can also provide some perspective here. As mentioned below, most meteorites come from asteroids that have not undergone differentiation, meaning that the chemicals have not separated due to any process. These are called chondrites, composed of stone which formed at the beginning of the solar system and do not exist on Earth, except when they fall. By examining these meteorites, we gain a better understanding of the early solar system, which allows us to better understand how our planet has evolved from that state to the way it is now.










The Moon is another fantastic place to study planetary science. While a grey, bland looking place, we have learned much about the history of our planet and solar system by looking at Moon rocks. Semi-frustratingly, only 1 geologist was part of the Apollo missions, and if we continue toward exploring the Moon and Mars via human missions, I hope we bring more scientists along!

Below, I actually got to touch a Moon rock! Of course, it didn't feel much different from any other rock, but it was very cool to feel connected to something 384,000 km away!



One aspect of the museum I, sadly, do not have any pictures of, was the artistic exhibit. Along with the scientific, meteorites have inspired artistic and even spiritual curiosity. The rest of the exhibit was dedicated to works of art created with or inspired by meteorites. It was a refreshing experience, learning about how these artists perceive meteors and incorporated these perspectives into their work. It was a side to the subject I had not experienced before.

So there you have it, a crash course on meteorites. Dangerous? Yes. Interesting and educational? Also yes. I hope you enjoyed the tour as much as we did, thank you all very much for reading and we'll see you in the next one!

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