tholin

Tholins are complex organic molecules that form when ultraviolet light or charged particles irradiate ice rich in nitrogen and methane. They are commonly found on the surfaces of outer solar system bodies such as Titan, the largest moon of Saturn, and Pluto. The term "tholin" was coined by astronomer Carl Sagan and his colleagues in 1979, derived from the Greek word "tholos" meaning cloudy, referring to their hazy appearance.

These molecules are typically reddish-brown in color and have a macromolecular structure, meaning they are large, complex polymers. Their exact chemical composition can vary depending on the starting materials and the energy source involved in their formation. On Titan, tholins are believed to be responsible for the moon's orange haze and its dark surface features. They are thought to be a significant component of Titan's organic chemistry and may have played a role in the origin of life on Earth.

The study of tholins is important for understanding the chemistry and evolution of planetary bodies in the outer solar system. Laboratory experiments that simulate the conditions on these celestial bodies have successfully produced tholins, allowing scientists to study their properties and potential implications. Their presence suggests that complex organic chemistry can occur in cold, distant environments, broadening our understanding of the potential for life beyond Earth.