THE UNITED KINGDOM INFRARED TELESCOPE
ANNUAL REPORT
1997

2.3. Solar System

Dr. Dale Cruikshank and co-workers obtained the best 3-4 m spectrum of Iapetus' dark side (which is five times less reflecting than its bright hemisphere) ever recorded, detecting an absorption feature near 3.3 m due to nitrogen rich organic molecules. Observations are continuing in 1998 to better define this band and an unidentified band detected at 3.85 m, both on the dark and bright sides of this enigmatic moon of Saturn.

Dr. Alan Harris and collaborators obtained spectrophotometry in the 10 m band of two near-Earth asteroids. In combination with measurements at longer infrared wavelengths from the Infrared Space Observatory, the UKIRT measurements allowed the sizes ( 1 km) and albedos (0.35 at 10 m) to be determined. These values have important theoretical implications for the formation and nature of near-Earth asteroids which in turn increases our understanding of the role played by such objects in the development and evolution of the inner planets of the solar system.