Final answer:
The Huygens probe's photographs revealed Titan's ancient hydrocarbon lake shore, boulder-strewn plains of water ice, and geological features shaped by a methane-based hydrological cycle.
Step-by-step explanation:
The photographs from the Huygens probe revealed that it landed on the shore of an ancient hydrocarbon lake on Titan, showing features such as drainage channels and an atmosphere with a deep orange sky. Despite the low brightness of the Sun, the images were clear enough to show a flat, boulder-strewn plain. The boulders and surface were composed of water ice, hard as rock at Titan’s frigid temperature of 94 K (-179 °C). Furthermore, cassini orbiter radar and infrared imaging have outlined Titan's complex geological activity, with large methane lakes and a plethora of erosional features, indicating a methane-based hydrologic cycle similar to Earth’s water cycle but with methane and ethane as the working fluids.