The Apollo 12 Suprathermal Ion Detector Experiment on the surface of the moon observes magnetosheath plasma as the moon passes out of the earth's magnetosphere. The first six months of SIDE data in the sheath were analyzed for this thesis. A composite display of the energies and magnitudes of fluxes was presented for each magnetosheath crossing. Interesting features of the sheath were labeled on the composite display and later illustrated by individual energy spectra. For the magnetically disturbed month of July, 1970, a third type of display presented all of the energy spectra plotted vertically versus time. The observed features of the sheath include: 1. High energy peaks (~1kev to 3kev) associated with the boundaries and with disturbances in the sheath 2. A sharp transition between two intensity levels, suggesting a sudden exit from a high density region or a sudden change in flow direction 3. Two types of magnetopause crossings 4. Hydromagnetic waves or turbulence near the boundaries 5. A strong correlation between sheath data and geomagnetic activity.