The 42-kilometre-wide gap in Saturn's A ring discovered by Voyager is called the Keeler gap.
Voyager spacecraft images revealed the feature in Saturn's outer A ring, and it was named for astronomer James Edward Keeler. The gap lies roughly 250 kilometres from the ring's outer edge and is about 42 kilometres wide. It is narrower than the much larger Encke gap, another prominent division within the A ring.
The Keeler gap is maintained by Daphnis, a small moon that orbits inside it. Daphnis's gravity sweeps nearby particles away and creates waves along the gap's edges. Because the moon's orbit is slightly inclined to Saturn's ring plane, it also produces vertical ripples that rise above and below the otherwise extremely thin ring system.
The Colombo and Maxwell gaps are different named features in Saturn's ring system, while the Encke gap is a separate, wider A-ring gap associated with the moon Pan.