Named for discoverers, the large, easily visible gap in the rings is known as the Cassini division, while the narrower outer gap is the Encke division. Illuminated from below and to the right, the rings cast a shadow onSaturn's upper hemisphere, interrupted where sunlight streams through the Cassini division and creates a light blue streak. At the left, Saturn also casts a stark shadow acrossthe planet girdling rings. On July 1, the Cassini spacecraft is scheduled to fire its main engine and enter Saturn orbit.