Meteorite’s Favorite Places Since the 1900's
Japanese Antarctic Research Expedition teams have been discovering a large number of meteorites in Antarctica, mostly near a mountain range. With 10 major ice sheets responsible for the movement of the South Pole ice towards continental areas, ice in Antarctica is known to be extremely mobile. The ice, when it reaches the continental area, either evaporates or falls into the sea. Taking into account this behavior, high density of meteorites in Antarctica does not necessarily mean they were accumulated over a long period. Instead, these ice sheets might have swept them towards the Yamato Mountain Range where most of them were discovered. This also happens due to strong winds that sweep snow and ice outwards. When the mountain range is encountered, it either melts or evaporates, revealing and leaving behind the meteorites. Since none of the meteorites were seen falling and were discovered only later on, we came to the conclusion that a meteor shower took place a few years before 1979.
For those who are curious about how we came to the above conclusion and the tools we used, read on!
About the Meteorites Dataset
This dataset contains details (id, location, class, mass, etc.) about meteorites that have hit Earth since the 1900’s until early 2000. They are further classified as ‘fell’ and ‘found’ which indicate whether the meteorite fall was observed (fell) or was directly found on Earth (found). While there are a number of reasons why this may have happened, in this post, we plan to focus on most frequent meteorite hit places and propose theories that can help justify their frequent occurrence.
A Snapshot of the Dataset
Plan of Action
We did play around with the data a little before we gained a clearer path to follow. Here’s how we zoomed in on the top 10 places where meteorites were most frequent in occurrence:
- Filtered top 10 years that have the highest number of records (since the number of records isn’t explicitly stated, we decided to use the class attribute as records).
- Filtered the class that occurred most frequently in the top year.
- A world map displaying all the locations of this class in the top year.
Tableau for the Basic Graphs
With the help of Tableau, we drew few basic graphs to get a few insights like the most frequent classes and the number of records they hold, just so to have an idea of what we are getting into.
[Note: The number of records in the above graph counts the number of rows and is automatically generated by Tableau].
Since L6 has the highest count of records, we decided to dig a little more into its characteristics to see if we could find any useful information that might help us understand why it is such a common occurrence. Here’s what we found:
- L6 belongs to a class of meteorites known as ordinary chondrites which are the most frequent objects to fall on Earth.
- They usually originate from a gap in the asteroid belt known as Kirkwood gaps.
- They contain low (hence the ‘L’) iron and nickel content (roughly 4–10%)
- Based on the nomenclature of meteorites, L6 is believed to undergo extensive metamorphism and thus, attains a homogenous structure.
On a hunch, we decided to check the meteorites of highest mass.
Turns out Iron IIIAB has the highest mass but with only 285 hits. Here are some of the facts about Iron IIIAB:
- These meteorites are the cores of the once intact asteroids.
- They are swamped with Iron (hence the name) but also contain large amounts of Nickel and Cobalt.
A Bar Graph Reflecting Fell and Found Ratio
Insights so Far
- L6 is the most frequently occurring class of all meteorites.
- Iron IIIAB has the highest mass of all meteorites.
Moving on to the Code:
[Note: The dataset was imported into a database and the incorrect data points were quickly erased before moving on to the filtering. The Python code uses SQL extensively for filtering.]
An Overview of the Dataset on the World Map
Filtering the top 10 years
Latitudes and Longitudes of the Places Where H4 Meteorite Hit in the Year 1979
10 places were hit in 1979 by H4 class meteorites. Mapping them on a world map:
[Note: 1,2 and 3 are extremely close to each other and look the same from a far view.]
The Top Places Where Meteorites Hit
- Yamato, Antarctica
- Namibia, Africa
- Near Great Victoria Desert Nature Reserve, Western Australia
- Near Mc Murdo Station, Antarctica
- Mexico
- United States
Out of 709 total H4 hits in 1979, Yamato (-71.5, 35.66667) has 700 hits, making it the most frequently hit place.
A Few Quick Facts Found About the Meteorites in Yamato, Antarctica
- There are over 4,000 meteorites collected during a Japanese search during 1979–1980.
- Previously, Japanese Antarctic Research Expedition Teams had collected 1000 other Yamato meteorite specimens. Their previous discoveries can be found here.
- The search party found a lunar meteorite and discovered as many as 1000 micrometeorites by melting roughly 36 tons of ice.
- All of them were found to be ordinary chondrites (originating from Kirkwood gaps) and include eucrites, diogenites, ureilites and stony irons.
A Detailed Satellite View of Yamato
This and other locations have a dark patch of ground around them. Since satellite images usually depict volcano remnants or burnt areas as black or dark brown, we plotted the volcanoes that had occurred in the past in Antarctica.
There aren’t any volcanoes anywhere near Yamato which led us to the conclusion that the area around it should be due to the ground burning up from the meteorite’s impact.
References
- Meteorite Data- Kaggle.com.
- Python Code for the Above Process-github.com.
- Yamato Discoveries- Harvard.edu
- A Detailed History of Japanese Antarctic Research Expedition- books.google.co.in
