A dark companion in transit across a bright stellar disk causes a decrease in the photometric signal. For the solar system this decrease amounts to about 0.01% for terrestrial-sized planets, and about 1% for Jupiter. If we assume that a star has a planetary system similar to the solar system, with a randomly oriented ecliptic plane, the probability of the occurrence of a occultation in one month is of the order of only 0.5% (Borucki and Summers 1984). However, from the large database that STARS will provide, it will be possible to carry out an automated search. Moreover, the temporal resolution will be adequate to study the ingress and egress of any system so discovered. In addition it will be possible to study the transit of circumstellar clouds across the images of T Tauri stars (Doyle and Collier Cameron 1990).