Hello, this is Scott Manley and I'd like to talk you through this video
I created showing the rate of discovery of asteroids for the last 30 years or so starting in 1980.
Now what you see here is a Top-down view
of the inner solar system with four planets in the middle and on the edges you can see Jupiter.
What you also see is a large number of 
green, yellow, and red spots,
denoting the position of asteroids.
The coloring is primarily to indicate 
how close they can come to the Earth.
Green are main-belt asteroids,
 yellow cross the orbit of Mars,
and red cross the orbit of Earth.
Also as asteroids are discovered,
we flash them white to make them more obvious.
Now if you look in the bottom left
There are two numbers. The first is the year 
and the second is a number of asteroids 
known on that date.
Now you can see this number grows as more objects were discovered by astronomers.
In addition, the highlighting of the discovery location lets you see patterns in the discovery process.
The most obvious pattern is that most objects are being discovered
opposite to the direction of the sun.
And this of course makes total sense since you're going to be looking for these things in nighttime skies.
Sometimes you see a big flash of discoveries lined up with another planet.
Scientists were perhaps looking for new moons around these planets,
but found asteroids as well.
In the 1980s most imaging is being done with photographic plates
but by the time the mid-nineties roll around
electronic imaging becomes the standard.
This gives a significant increase to the discovery rates, since the turnaround time for image processing and analysis gets much faster.
When you're trying to discover objects moving across the night sky
It's very important that you follow up in the observations before the object moves too far and is lost.
Now by the late 90s a number of dedicated
asteroid discovery programs are in full flow.
These combined electronic imaging with automated image processing and follow-up.
Hundreds of new objects are being 
discovered every day
and new patterns of discovery become evident.
if you watch you can see the discovery rate pulsing
roughly twice a second. This corresponds to the lunar cycle.
During a full moon it is harder to discover faint objects since the moonlight makes the background sky brighter.
There's also a sparse dead spot around a five o'clock position.
Apparently this corresponds to the cloudy season in Arizona where a number of these automated surveys are based.
Now by mid 2000 we're starting to see hundreds of thousands of known objects,
and its getting very crowded in the inner solar system.
But you need to appreciate the distances here are a huge.
One pixel at the highest resolution is still five hundred thousand kilometers.
So all those objects apparently buzzing the earth are still a long way out.
And now for a few seconds, you're going to see the discovery pattern
of W.I.S.E.:
  the Wide-field Infrared Survey Explorer
That was a space telescope designed to image the entire sky in infrared
And so we're almost up to the present day, and we have over half a million asteroids in our database.
I'm Scott Manley.
Thanks for watching.
