Saturn’s Moon Titan Seen in New Light
October 28, 2013
Thanks to a change of seasons on Titan, Saturn’s largest natural satellite, scientists with NASA’s Cassini mission are getting a much clearer view of the lakes and seas in that moon’s unusual northern regions. Since Cassini’s arrival at Saturn in 2004, thick winter clouds and haze have shrouded Titan’s northern regions. (A year on Saturn lasts for about 30 Earth years.) Now, with the appearance of northern summer, the clouds and haze are disappearing. With a better view–and brighter sunlight–Cassini’s cameras have been able to capture new details about Titan’s bodies of liquid and surrounding terrain. Scientists think this new information will provide insights into the formation of these bodies as well as the moon’s cycle of rainfall and evaporation.
Titan is the only other body in the solar system, beside Earth, known to have stable liquid on its surface. On Earth, the most abundant surface liquid is water. But because Titan’s atmosphere is extremely cold, any liquid water or water vapor there would quickly freeze. Instead, Titan’s rivers and lakes are filled with such hydrocarbons as ethane and methane. These chemical compounds, which are found in natural gas, have a very low freezing point. Clouds of methane and ethane also float above the surface. The clouds sometimes rain methane as part of Titan’s hydrologic cycle.
During Titan’s northern winter, Cassini scientists relied on radar, which can penetrate thick clouds and haze, to study the surface. Aided by a summer sun, Cassini scientists have been able to focus the probe’s visual and infrared cameras on the lakes and seas. In addition to clearer views of these bodies, the new images have revealed a previously unknown bright area that scientists think is similar to salt flats on Earth. On Earth, salt flats are areas once covered by water, which evaporated, leaving behind mineral deposits.
Since the discovery of seas, lakes, and rivers on Titan, scientists have puzzled over why most of these bodies are found in the moon’s northern regions. Theories explaining their formation have ranged from the collapse of volcanic mountains to the development of sinkholes. The new images could help scientists unravel this mystery.
Additional World Book articles:
- Astronomy (2005) (a back in time article)
- Astronomy (2006) (a back in time article)
- Close Encounters with Saturn (a special report)