I hadn't quite finished this, I wanted to record a voiceover, but a friend submitted it before I was ready.
So essentially the video shows asteroids which are known, so in the early portions around 1980 we have less than 10,000 and by the start of this month we have over half a million. Asteroids are highlighted on discovery and within a second they fade to the colour appropriate to their orbit (Green, Yellow and Red), asteroids are usually observed intensely around discovery and once an orbit is determined observers can go back and follow up to refine the exact elements, I only show the discovery, not follow up measurements. This does mean that a number of the objects that are being plotted have orbits that may be so poorly determined that they are 'lost in space' because they were only observed for a short time and by the time people attempted to follow up they were lost.
At the start of the videos, the 1980's, CCD's weren't used for astronomy, photographic plates were the primary technology for imaging the sky, furthermore, there were no digital systems for identifying asteroids on these plates, so while many asteroids were no doubt imaged they were generally not of interest to the observers who were probably taking nice pictures of nebula or other photogenic phenomena. Many of the discoveries in the 1980's were still made visually by minor planet hunters who knew what they were looking for. One of the earliest 'bursts' in the video is most likely related to observations of Jupiter searching for new moons around the giant planet, they'd look for objects moving on the plates and then make an orbit determination to see if it was a moon, it's waaaaay cooler to find a moon since they're a rarer commodity, but if you merely find an asteroid at least you get a chance to name it.
By the time we get to the mid 1990's we start to see automated sky search programmes like LINEAR, LONEOS, Spacewatch and the Catalina Sky Survey and these are primarily searching for asteroids in opposition since they're closer to Earth and at peak brightness so you can see a discovery cluster radiating out from the Earth.
In the last 8 months you see WISE which is a satellite performing a full sky survey in the Infrared, its scans the sky at 90 degrees to the sun, so its discovery pattern is very distinctive.
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