A division in Saturn’s rings, about 270 km from the outer edge of the A Ring. It lies 136 500 km from Saturn’s centre and is about 35 km wide. The small moon Daphnis (diameter c.8 km) orbits within it. The boundaries of the gap are not circular, and show radial wave-like variations as a result of resonances with the moon Prometheus which orbits just outside the A Ring. Its existence was confirmed by the Voyager probes; it is named after the American astronomer James Edward Keeler (1857–1900), who saw it in 1888.