Reported is a study to determine the effect of planetarium instruction in terms of immediate attainment, attitude, and retention in the teaching of selected celestial motion and non-celestial motion concepts, when contrasted to or combined with the inquiry activities utilized by the nationally developed science curricula. Observations were made on three treatment groups at both the junior high school and college levels. One hundred eighth-grade students in a school system in New York participated in the study which was replicated at Edinboro State College, Pennsylvania. Investigator-developed instruments were administered six weeks after the treatment to measure retention. An astronomy related semantic differential instrument was designed to measure student perceptions concerning the unit of instruction and astronomy in society. Results indicated that: (1) the group (Treatment Group I) which experienced the orientation session did significantly better on content learning than the group which did not; (2) the combined treatment group (III) was the only group which significantly benefited from the treatment; (3) all groups showed minimal loss of content achievement on the retention test; (4) no interaction effect between treatment and retention was noticed on posttest data for the college treatment groups; and (5) the planetarium group (I) in both junior high and college studies had the greatest positive perception change. (Author/PEB)