Achievement

Contrary to previous understanding, IGERT trainee Nate Kaib and his advisor T. Quinn used computer simulations to show that the inner Oort Cloud (in the far outer part of the solar system) is a significant and perhaps the dominant source of long-period comets. They used this result to place the first observationally motivated upper limit on the population of bodies orbiting in this region of the solar system. Because this reservoir supplies the Earth-orbit-crossing comets produced during comet showers triggered by close stellar passages, they were able to show that these events have most likely not caused any major extinction events in the Earth's fossil record.