ET on Your Roof! – Our Wide Sky

ET on Your Roof!

August 15, 2017

As the Earth travels through space in its journey around the sun, it is bombarded with all kinds of material from space. Most of it is obliterated through friction in our atmosphere. Sometimes, this is visible in the form of meteorites and meteors, lighting up the sky. But invisible tiny pieces of space dust make their way through atmosphere and land almost everywhere.

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It’s likely that micrometeorites are making their way to a roof or pavement or road or a garden near you right now.

An estimated 30,000 tonnes of micrometeorite material hit the atmosphere every year. 10% of this finds its way to the service of the Earth. In a year an area as small as 50 m² will get an average of 50 objects around 0.1mm in size landing on it. This means that your roof has micrometeorites. It means that as you walk around the city you’re walking on micrometeorites. 

The study of micrometeorites is not new but the study of micrometeorites in urban areas is new.

In his new book, In Search of Stardust, Jon Larsen documents how, over the past 10 years, he has found ways to discover micrometeorites in urban environments, something previous considered impossible.

His book is a beautiful photo essay, with scanning electron microscope (SEM) images and photographs of these tiny pieces of space dust that have landed everywhere.

One of the most difficult things in the search is determining whether a piece of dust is extraterrestrial, is naturally occurring on the Earth or is made by humans. As you can imagine separating tiny pieces of dust into the three categories is no easy task. Larsen not only shows us what the micrometeorites look like, he shows us what the pretenders look like.

​Finding the rare space particles in a pile of dust is not easy, and even when you have sifted for size, and sorted for magnetic particles, you still have to look closely at tiny grains to check for welding spheres, asphalt, dust from truck brakes, and even colourful artefacts created in fireworks. These are beautiful in themselves, but must be identified if you are to finally identify a rare micrometeorite.

A micrometeorite my have started its journey billions of years ago, as stars were forming. It may have floated through space joggled by the gravity of stars and planets through the interstellar medium, finally entering our solar system and caught up in the path of the Earth. It enters our atmosphere and is shaped and molded by friction on the last part of its journey through atmosphere. These grains of dust end up being less than half a millimetre in size and can be stunningly beautiful species of glass or metal with nickel or iron on beads attached.

Larson's book is a beautiful odyssey through his discoveries in many parts of the world as he travelled looking for tiny extra terrestrial objects. He picked them out  large quantities of dust from rooves and pavements in urban areas.

The book is an easy read and it’s not too scientific. There is some geology and microscope terminology, and enough scientific text just enough to get you interested. The book is mostly pictures and the pictures are arranged to show the symetry and diversity of dust. Images of the meteorite specimens are stunning. There are scanning electron microscope images of surfaces and cross sections to shwo you what is on the inside of these long-distance travellers.

There is enough context to explain where they’ve come from what happened to them as that travelled through the atmosphere.  He describes their morphology and the chemical composition, and the beautiful structures that appear on them have after their searing journey through space to the surface of the Earth. 

The search for micrometeorite like a treasure. The target is tiny and rare, but it’s in your backyard and that’s what exciting.

Purchase In Search of Stardust: Amazing Micrometeorites and Their Terrestrial Imposters to purchase the book and see for yourself. Maybe you'll catch is the micrometeorite hunting bug and find some them in your backyard.

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