Introduction
Roughly 5 billion years ago, a ball of collapsing hydrogen and helium suddenly ignited its nuclear furnace and became our Sun. A disk of material began to form around it, and eventually turned into the nine planets. But not all the material in this disk became the planets. Some of it became comets, asteroids, and other objects at the outskirts of our Solar System - the Kuiper Belt. All of these can turn into a source of small dust particles. As they approach the Sun, comets heat up and release volatile material (like water) and dust, forming cometary trails. All other solid surfaces can turn into sources of dust due to mutual collisions or bombardment by interstellar and interplanetary dust. Small dust particles in the Solar System are relatively short lived. They lose energy due to drag, and follow a slow spiral towards the Sun. Many of them never make it closer than Jupiter?s orbit. Jupiter is very effective at scattering the inward moving grains, acting as a 'gate-keeper' of the inner Solar System. The small fraction of the particles that sneak by Jupiter, or those that were born inside Jupiter?s orbit, continue spiraling towards the Sun. As they heat up they lose mass like a mini-comet. Eventually radiation pressure gets larger than the gravitational attraction of the Sun, and these tiny travelers end up zooming out of our Solar System.

The density distribution of dust across the entire Solar System reflects the strength and the distribution of the sources, as well as the speed of the transport. This works very much like a sand delivery truck speeding down the highway. There is always a cloud of dust in the air, even though each of the particles lives for a short time only. The cloud changes as the truck speeds, slows down, or comes to a halt.

The very same processes are expected to work in other planetary systems. The structures that we see in dust disks around other stars are tell-tale signs of planets within the disk. The Student Dust Counter on the New Horizons Mission will measure the density variations along its orbit, which cuts across the entire Solar System. These measurements will allow us to verify our theoretical models about the sources and the transport processes of dust that makes up our own dust disk. It will also open up new ways to use similar structures seen in the dust disks around other Stars to learn about the planets there.

Want to know more about the mission and the Student Dust Counter? Then come take a little time to look around the website and learn!