Puzzling Colors of Objects in the Kuiper Belt

Presented by Prof. William Romanishin, OU

A half century ago, astronomers Kuiper and Edgeworth independently hypothesized the existence of a class of objects orbiting the Sun beyond the orbits of Neptune and Pluto. After much observational effort with large telescopes to actually find such objects, success came only in 1992, when Dave Jewitt and Jane Luu found object 1992 QB1, the first object (besides Pluto) orbiting past Neptune. There are now over 60 such objects known. For the past 2.5 years, Steve Tegler (of Northern Arizona University) and I have used large telescopes to study the colors of these very faint newly found members of the Solar System. In this talk, I will first give an introduction to the history and current status of our knowledge of the Kuiper Belt. I will then discuss the work we have been doing on the colors of Kuiper Belt objects. We have found that the Kuiper Belt objects have a bimodal color distribution, with one group showing colors similar to reflected sunlight, and the other group redder than any other minor bodies in the Solar System. At present, we do not know why there are two classes of Kuiper Belt objects.