I love showing this youtube video about the asteroid discoveries in our inner solar system. Scott Manley takes the positions of detected asteroids, and highlights them as they are discovered. The final colors indicate how close they are to the Earth's orbit:
Red= Earth Crosser
Yellow= Earth Approachers (coming within 1.3 AU)
Green = All Others
The discoveries tend to follow the Earth's orbit because asteroids are best seen opposite the sun, when they are most illuminated. It's also interesting to see that discoveries go way up in the 1990's, when satellites start coming online. This is a cool way to highlight the importance of technological advances to scientific discoveries.
And, if you think this looks like a crowded mess, the Kuiper belt around the outer solar system is about 20 times as wide!
I love videos like this because they are sobering reminders of the vastness of space. As dense as these asteroids look, they won't collide with each other. In fact, movie scenes of spaceships dodging chunks of rocks in the Asteroid Belt is just plain wrong. The Asteroid Belt is mostly made of empty space. Yup. That's right. That's how BIG space is!
In the spirit of the late Carl Sagan, I sometimes think about how tiny the Earth is in this video. I really try to visualize it's place in our tiny corner of the Milky Way. It's just one planet circling one average sun with a half million other chunks of rock. Then, sometimes I think about the wars fought over this planet - the wars of death and human misery that were caused by zealous rulers intent on owning a piece of this tiny rock. You wouldn't be able to see the boundaries we fight so fervently for. Astronomy is, like so many people say, a humbling field. In the grand scheme of things, everything just seems so . . . small.