Two Solar System Puzzles Solved

How did icy comets obtain particles that formed at high temperatures, and how did the particles acquire rims with different compositions? Carnegie scientists are the first to model the trajectories of refractory particles in the unstable disk that formed the Solar System. They found particles could have been processed in the hot inner disk, and then traveled to the frigid outer regions to end up in icy comets. Their meanderings could help explain the different rims.