Meteorites

We will explore the dataset posted on 2019-06-11 edition of Tidy Tuesday. Link to original post: Meteorites

library(tidyverse)
library(gganimate)
meteorites <- readr::read_csv("https://raw.githubusercontent.com/rfordatascience/tidytuesday/master/data/2019/2019-06-11/meteorites.csv")

There can be lots that can be discovered from the data, however, today we will only focus on the year and meteors that fell to Earth.

meteorites
## # A tibble: 45,716 x 10
##    name       id name_type class    mass fall   year   lat     long geolocation 
##    <chr>   <dbl> <chr>     <chr>   <dbl> <chr> <dbl> <dbl>    <dbl> <chr>       
##  1 Aachen      1 Valid     L5         21 Fell   1880  50.8    6.08  (50.775, 6.~
##  2 Aarhus      2 Valid     H6        720 Fell   1951  56.2   10.2   (56.18333, ~
##  3 Abee        6 Valid     EH4    107000 Fell   1952  54.2 -113     (54.21667, ~
##  4 Acapul~    10 Valid     Acapu~   1914 Fell   1976  16.9  -99.9   (16.88333, ~
##  5 Achiras   370 Valid     L6        780 Fell   1902 -33.2  -65.0   (-33.16667,~
##  6 Adhi K~   379 Valid     EH4      4239 Fell   1919  32.1   71.8   (32.1, 71.8)
##  7 Adzhi-~   390 Valid     LL3-6     910 Fell   1949  44.8   95.2   (44.83333, ~
##  8 Agen      392 Valid     H5      30000 Fell   1814  44.2    0.617 (44.21667, ~
##  9 Aguada    398 Valid     L6       1620 Fell   1930 -31.6  -65.2   (-31.6, -65~
## 10 Aguila~   417 Valid     L        1440 Fell   1920 -30.9  -64.6   (-30.86667,~
## # ... with 45,706 more rows

First we will clean the data and focus only on the meteorites that fell.

meteors = meteorites %>%
  filter( fall == "Fell") %>%
  mutate( mass = mass / 1000 ) %>%  # convert from grams to kg
  select(name,mass,year,lat,long) %>%
  na.omit()
meteors %>%
  filter(year >= 1600) %>%
  count(year) %>%
  ggplot(aes(x=year,y=n))+
  geom_line( )+
  theme_bw()+
  labs(title="Many Meteorites Where Detected in Recent Centuries")

We notice that there have been many sightings of fallen meteorites in recent centuries, and we see that that there has been a gradual uptick in the number discovered up until the 1940s. This could be due to more people being able to watch the skies or better access to technology as time passes.

Though in the past 50 years there hasn’t been as many detections, which can come across as odd, since due to modern and sophisticated technology, surely we would be able to detect more meteorites? The answer could lie in the fact that meteorites are just really rare events.

Let’s look at the mass distribution of meteorites

custom_length = 10^seq(-4,4,1) 


ggplot(meteors, aes(x = mass)) +
  geom_histogram(bins = 30, fill = "#05377b") +
  scale_x_log10(label = paste0(modify(custom_length , function(x) {
    if (x > 1) {
      trunc(x )
    } else{
      x
    }
  })
  , "kg")  ,
  breaks = custom_length ) +
  labs(title = "Most Meteors Weighted Around 0.1kg to 100kg ",subtitle = "Mass Distribution of Meteors With Log Base 10 Scale", x = "Mass (kg)", y = "Count")+
  theme_minimal()+
  theme(panel.grid.minor.x = element_blank(),
        axis.line = element_line())

The masses of meteorites varied quite drastically, but when placed on a sensible scale, we see that the most common meteorite weight was about 5kg. The meteorites can weigh as little as a 0.1 grams to an enormous 10,000kg, which is the same weight as the bell of Big Ben!

Below is an animation that shows the year and location of recorded meteorites.

For the static version see below

We see many recorded landings in densely populated areas such as: Europe, The East Coast of America, and India.

We notice that there are spots in the world that do not have any recorded meteorite landings. This includes places like: Northern Australia, Western China, Northern Russia, The Amazon, and so on .It seems unlikely that meteorites will not land in uninhabited places across the globe and we do not have many instances of recorded landings in the ocean, so we could attribute these blank areas as places where nobody was around to detect the falls.

Just because we didn’t see it, it doesn’t mean it didn’t happen.