Smog in space: Saturn's hazy moon of Titan

Humans like to think of the Earth as a unique body in the solar system. Indeed, in as much as our planet is the only planet capable of hosting life, Earth stands alone. But aspects of our planet appear in other celestial bodies -- smog, for example. As this image from NASA shows, commuters and environmentalists who complain about air conditions should probably avoid Saturn's moon Titan.

In a study published in the Proceedings of the National Academy of Sciences, researchers used data from NASA's Cassini spacecraft to analyze the atmosphere of Titan, Saturn's largest moon. They looked at the upper layers of Titan's atmosphere, where nitrogen and methane combine to create thick aerosols. Scientists hope to use the data from Titan to help predict the behavior of smog here on Earth.

Solar radiation causes the molecules in Titan's ionosphere to become positively and negatively charged. These particles begin to coalesce, forming more complex aerosols. These aerosols swirl through the moon's atmosphere, thickening the sky and slowly collected into even larger particles. Eventually, they form the heart of the physical processes that rain hydrocarbons on Titan's surface and form lakes, channels and dunes.

The image above was taken with Cassini's visual and infrared mapping spectrometer (VIMS.) The atmosphere of Titan is so thick in parts that the majority of visible light is absorbed. But using VIMS, scientists were able to piece together a visual image of the moon.