Titan, once thought to be the largest moon in the solar system, turned out to be slightly smaller than Ganymede when photographed by Voyager 1. The surface of Titan is obscured by a dense atmosphere of nitrogen and methane, which made the moon appear larger in telescopic observations.
Although the atmosphere looks featureless when photographed from afar, some banding was detected in specially processed Voyager 1 images.
Voyager 2 Image of Titan. NASA Press Release #P23929.
A color-enhanced image from Voyager 1 shows high altitude haze layers that occur 500 kilometers (310 miles) above the main cloud layer of Titan. Below the orange cloud layer, clouds of methane may rain onto the surface. The surface of Titan could even have "oceans" of liquid hydrocarbons.
NASA Press Release #P23108.
Voyager results indicate that Titan is more like Earth than any of the planets. The abundance of carbon components may make Titan a natural laboratory to study the most primitive organic chemical reactions that were present on Earth some 4 billion years ago.
Bands in the northern hemisphere and equatorial regions of Titan as seen by Voyager 2. NASA Press Release #P24067.