for their discovery and characterization of trans-Neptunian bodies, an archeological treasure dating back to the formation of the solar system and the long-sought source of short period comets.
Prior to the detection of the first trans-Neptunian objects by Jewitt and Luu in 1992, little was known about the content of the solar system between the orbit of Neptune at 30 AU and the Oort cloud, the source of long period comets beyond 10,000 AU. Now we know that the region between 30 and 50 AU is populated by tens of thousands of icy bodies with diameters in excess of 50 kilometers. These grew by the accretion of solids during the early stages of planet formation until some undetermined process increased their velocity dispersion to the extent that accretion terminated. Subsequently, owing to their large separations, these bodies escaped further collisional evolution. Thus they provide our best record of the early stages of planet formation.
The search that culminated in the discovery of the first trans-Neptunian body took 5 years. It was initiated while Jewitt was an Assistant Professor at MIT and Luu was his graduate student.
Astronomy is arguably the oldest science. Observations of the motion of heavenly bodies date back more than 2,500 years. Nevertheless, as recently as 1992, immediately prior to the detection of the first Kuiper belt objects (KBOs) by Jewitt and Luu,1 little was known about the contents of the solar system beyond 30 AU.2 Distant bodies are dim because they reflect little sunlight back to Earth and our most powerful telescopes can only image small angular regions at a single pointing. Thus searches for widely-spaced, faint images are tedious and resource intensive. Before Jewitt and Luu’s discovery, Pluto and its large satellite Charon were the only directly detected bodies orbiting beyond Neptune.
Comets provide indirect information about reservoirs of bodies beyond 30 AU. Although comets are directly detected only when they come within a few AU, their orbits can be traced back to show where they came from. By 1950 it had been established that most long-period comets were visitors from distances in excess of 10,000 AU and that their orbits were randomly oriented with respect to the mean orbit plane of the solar system. These facts led Jan Oort to hypothesize that comets are stored in an enormous spherical cloud beyond 10,000 AU and that gravitational deflections by nearby stars are responsible for injecting those we detect into the inner solar system. Oort’s model is widely accepted and the hypothetical comet cloud carries his name. However, his assumption that short-period comets are descendants of long-period ones did not fare as well.
David C Jewitt was born in 1958 in England and is currently a professor at the University of California, Los Angeles and Director of the Institute for Planets and Exoplanets at UCLA. He graduated from the University of London in 1979 and received a Master’s degree in Science and a PhD in Planetary Science and Astronomy from the California Institute of Technology in 1980 and 1983 respectively. During the period 1983 to 1988 he worked as an Assistant Professor at MIT. From 1988 to 1993, he held positions as Associate Astronomer and Associate Professor at the University of Hawaii, where he became Astronomer and Professor in 1993, and where he continued to work until 2009. He is a fellow of the American Academy of Arts and Sciences, and a member of the United States National Academy of Sciences.
Jane Luu was born in 1963 in Saigon, Vietnam. Since 2001, she has been a member of the technical staff at Lincoln Laboratory, Massachusetts Institute of Technology. She received her Bachelor’s degree in Physics from Stanford University in 1984 and a PhD in Planetary Astronomy from MIT in 1990. In the years 1990 to 1994, she was a Postdoctoral Fellow at various institutions, namely, the Harvard-Smithsonian Center for Astrophysics, UC Berkeley and Stanford University. She was appointed Assistant Professor at Harvard University in 1994 and Professor at Leiden University, the Netherlands in 1998. The asteroid 5430 Luu is named in her honour.
