This incredible video by Scott Manley/Armagh Observatory (and recommended by Neil deGrasse Tyson on Twitter) shows the locations of all the known asteroids starting in 1980, adding more as they are discovered (highlighted in white so you can pick out the new ones.) But the final color of the asteroids tells you more about them: Earth crossing asteroids are red, Earth Approachers (with a perihelion less than 1.3AU) are yellow, while all others are Green.
In the video you can see the pattern of discovery follows the Earth around its orbit and most discoveries are made in the region directly opposite the Sun.
The orbital elements were created by Ted Bowell. See this webpage for more info.
More from the notes on You Tube:
“You’ll also notice some clusters of discoveries on the line between Earth and Jupiter, these are the result of surveys looking for Jovian moons. Similar clusters of discoveries can be tied to the other outer planets, but those are not visible in this video.
As the video moves into the mid 1990’s we see much higher discovery rates as automated sky scanning systems come online. Most of the surveys are imaging the sky directly opposite the sun and you’ll see a region of high discovery rates aligned in this manner.
At the beginning of 2010 a new discovery pattern becomes evident, with discovery zones in a line perpendicular to the Sun-Earth vector. These new observations are the result of the WISE (Widefield Infrared Survey Explorer) which is a space mission that’s tasked with imaging the entire sky in infrared wavelengths.
Currently we have observed over half a million minor planets, and the discovery rates show no sign that we’re running out of undiscovered objects.”