Data Visualization: Bolides
Click on the image above to see a dynamic animation that details the history of known bolide sightings.
Rusty Schweickart wrote this introduction to explain a bit more about bolides. “This is a really great interactive graphic by data visualization designer Carlo Zapponi. It dramatically illustrates the historic record of bolides that have been witnessed entering the Earth’s atmosphere around the world from 861 through 2012. Make sure to move your cursor around the graphic and to also look at the tabular display below the graphic. There’s lots of information here including maps of where the bolides were seen and links to the Meteoritical Society’s web page for each object.
And… what’s a bolide? You’ll find a good definition at the bottom of the page. However what most meteoriticists fail to mention is that bolides, fireballs, meteoroids, shooting stars, etc. are all small bits and pieces of either comets or asteroids. They are, in fact, small asteroids and comets. We don’t worry much about these little guys… they’re fun to watch entering the atmosphere and even more fun to find if pieces make it to the ground (these are called meteorites).
If you look closely at the meteorites on the linked pages you’ll note that most of them are iron/nickel. Don’t let that fool you! Iron/nickel asteroids are a small minority of the population. Most are stony or stony-irons, but it is the iron/nickel ones that make it to the ground and are a bit easier to recognize when you see one. Most of the NEOs that we worry about, however, are the stony types which make up the majority of the NEO population. Once they’re larger than ~30 meters in diameter they can do serious damage on the ground even if they don’t make it to the surface (e.g. Tunguska). When they get in the range of 150 meters in diameter they make it to the surface (and even below the surface!). These are the ones that B612 is committed to finding… and ultimately deflecting.”