Triton . Neptune I . ... Voyager 2 images showed active geyser-like eruptions spewing nitrogen gas and dark dust particles several kilometers into the atmosphere. ... Voyager 2 obtained this color image of Neptune's large satellite Triton during its close flyby on Aug. ... The polar frosts were sublimating because Triton's orbital and rotational motion causes the sun to shine directly on the polar cap for a period of several decades during Neptune's and Triton's long austral summer. ...