What are the dark streaks found in Triton’s polar region?

The dark streaks observed within the polar ice cap region of Triton are evidence of surface winds. These streaks are formed by dust particles that are carried by nitrogen gas escaping through vents in the moon's surface ice.

Specifically, at least two of these streaks—and potentially dozens more—are the result of active, geyserlike plumes that were observed erupting during the Voyager 2 flyby. These plumes carry entrained dust to heights of approximately 8 km (5 miles), after which the material is transported downwind for distances reaching up to 150 km (90 miles). While the exact mechanisms driving these plumes are not fully understood, their tendency to occur at latitudes illuminated vertically by the Sun suggests that incident sunlight plays a significant role in their formation.1