The terminator, the line dividing lunar day and night, moves across the disk to unveil ever more features as the Moon's phase grows to first quarter, gibbous, then full. Near the terminator the slanting sunlight casts long shadows, so here mountains and valleys stand out prominently. They become more easily visible if you brace the binoculars tightly against something to hold them very still. The Moon's major landmarks are easy for binocular users to learn. In addition to the features identified here, scores of smaller details can be seen in even a 5-power instrument.
Features often change appearance at different lunar phases.
The planet Mercury can sometimes be located during twilight with the naked eye, but binoculars make it much easier to pick up. Once found, however, this little planet only appears starlike. As with many astronomical objects, the accomplishment lies in finding it at all. Venus, on the other hand, will show its crescent phase in high-quality binoculars. In the summer and fall of 1610, Galileo watched Venus change phases in the evening sky.